perf(buffer previewer): improve performance

[linrongbin16]

I changed the internal implementation of communication between provider and buffer previewer.

In previous implementation, I'm using --bind=focus:execute-silent(echo {} > cache_file) to dump fzf's current pointer's line into a cache_file, and watch the file's change with uv.new_fs_event. then render the line (actually a file name) to the buffer previewer.

The uv's fs event is awesome, but binding echo to fzf could lead to stucking, since fzf's focus event is running in sync mode, not async. so when you typing fast, it could be quite laggy. I hate it.

In this PR, I use the fzf's experimental feature: curl localhost:port to get the fzf current status. It will output a json string with: {"current":{"index":97,"text": "lua/fzfx.lua"}}, the current.text is exactly the current fzf's pointer's line.

So I'm trying to get the current line data with uv.spawn, which is also async, it should have better performance. But actually I still met some performance bottle necks:

1. the json output of fzf status is super big, because it contains all the lines in the left side of fzf. I submit a question about this: https://github.com/junegunn/fzf/discussions/3611, hope I could partially query only the current field. For now I'm using a partial decoding method, to hack into the json and retrieve only the current field.
2. Render all the lines of a file could eat a lot of CPU. I rewrite the buffer previewer, and only render the lines in the previewer window. Thus the rendering should be lazy, e.g. only render the lines that user need to see.

Regresion test

Platforms

• [ ] windows
• [ ] macOS
• [ ] linux

Tasks

• [ ] FzfxFiles
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-R to switch between restricted/unrestricted mode, and the lines count is consistent when press multiple times.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file, and open the test/hello world.txt, test/goodbye world/goodbye.lua files.
  • Both fd and find works.
• [ ] FzfxLiveGrep
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-R to switch between restricted/unrestricted mode, and the lines count is consistent when press multiple times.
  • Use -w to match word only, use -g *.lua to search only lua files.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file, and open the test/hello world.txt, test/goodbye world/goodbye.lua files.
  • Both rg and grep works.
• [ ] FzfxBuffers
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-D to delete buffers, and delete the test/hello world.txt, test/goodbye world/goodbye.lua buffers.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file.
• [ ] FzfxGFiles
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-W to switch between workspace/current folder mode.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file.
• [ ] FzfxGLiveGrep
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file.
• [ ] FzfxGStatus
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-W to switch between workspace/current folder mode.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file.
  • Both with/without delta works.
• [ ] FzfxGBranches
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-R/CTRL-O to switch between local/remote branches.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to checkout branch.
• [ ] FzfxGCommits
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-A to switch between git repo commits/current buffer commits.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to copy commit hash.
  • Both with/without delta works.
• [ ] FzfxGBlame
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to copy commit hash.
  • Both with/without delta works.
• [ ] FzfxLspDiagnostics
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-W to switch between workspace/current buffer diagnostics.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file.
• [ ] FzfxLspDefinitions, FzfxLspTypeDefinitions, FzfxLspReferences, FzfxLspImplementations
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Go to definitions/references (this is the most 2 easiest use case when developing this lua plugin with lua_ls).
  • Press ESC to quit, ENTER to open file.
• [ ] FzfxLspIncomingCalls, FzfxLspOutgoingCalls
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Go to incoming/outgoing calls.
  • Press ESC to quit, ENTER to open file.
• [ ] FzfxCommands
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-E/CTRL-A to switch between user/ex/all vim commands.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to feed vim command.
• [ ] FzfxKeyMaps
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-O/CTRL-I/CTRL-A/CTRL-V to switch between normal/insert/visual/all vim key mappings.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to feed vim keys.
• [ ] FzfxFileExplorer
  • Press CTRL-J/CTRL-K to move down/up and preview contents.
  • Press CTRL-U/CTRL-R to switch between filter/include hidden files mode.
  • Press ALT-L/ALT-H to cd into folder and cd upper folder.
  • Use V/W/P/R variants (visual selection, cursor word, yank text, resume last).
  • Press ESC to quit, ENTER to open file, and open the test/hello world.txt, test/goodbye world/goodbye.lua files.
  • All eza/lsd/ls works.

[codecov[bot]]

Codecov Report

Attention: 260 lines in your changes are missing coverage. Please review.

Comparison is base (194d338) 75.17% compared to head (7cf30b5) 77.74%.

:exclamation: Current head 7cf30b5 differs from pull request most recent head e838972. Consider uploading reports for the commit e838972 to get more accurate results

Files	Patch %	Lines
lua/fzfx/detail/general.lua	30.37%	110 Missing :warning:
lua/fzfx/detail/popup/buffer_popup_window.lua	26.61%	102 Missing :warning:
lua/fzfx/cfg/_lsp_locations.lua	38.46%	8 Missing :warning:
lua/fzfx/detail/bat_helpers.lua	68.18%	7 Missing :warning:
lua/fzfx/cfg/vim_commands.lua	66.66%	6 Missing :warning:
lua/fzfx/detail/popup.lua	33.33%	6 Missing :warning:
lua/fzfx/cfg/lsp_diagnostics.lua	44.44%	5 Missing :warning:
lua/fzfx/cfg/vim_keymaps.lua	64.28%	5 Missing :warning:
lua/fzfx/cfg/git_branches.lua	57.14%	3 Missing :warning:
lua/fzfx.lua	0.00%	1 Missing :warning:
... and 7 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #584 +/- ## ========================================== + Coverage 75.17% 77.74% +2.57% ========================================== Files 51 51 Lines 6114 5757 -357 ========================================== - Hits 4596 4476 -120 + Misses 1518 1281 -237 ```

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