feat(previewer): enable buffer previewer for files

[linrongbin16]

Regresion test

Platforms

• [x] windows
• [x] macOS
• [ ] linux

Tasks

• [x] 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.
• [x] 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: 9 lines in your changes are missing coverage. Please review.

Comparison is base (817a9a6) 78.19% compared to head (ccb55bf) 78.13%.

Files	Patch %	Lines
lua/fzfx/detail/popup/buffer_popup_window.lua	14.28%	6 Missing :warning:
lua/fzfx/lib/switches.lua	75.00%	2 Missing :warning:
lua/fzfx/detail/popup.lua	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #591 +/- ## ========================================== - Coverage 78.19% 78.13% -0.06% ========================================== Files 51 52 +1 Lines 5755 5773 +18 ========================================== + Hits 4500 4511 +11 - Misses 1255 1262 +7 ```

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