fix(events.lua): Listen for default and user-configured sidebar_filetype close events

[03juan]

Creates default BufWinLeave autocmd and appends custom option.event if it differs from the default.

Fails silently using pcall if the other event already deleted the autocmd from line 192.

Closes #502

Tested with "print debugs"

local ok, _ = pcall(del_autocmd, autocmd)
if not ok then
  print("couldn't delete autocmd", vim.inspect(autocmd), vim.inspect(e))
else
  print("deleted autocmd", vim.inspect(autocmd), vim.inspect(e))
end

• [x] Closing with :q

• [x] Toggling

[03juan]

The close events are cleared correctly both when toggling and quitting:

• [x] Toggle
  • Before
  • After
• [x] Quit
  • Before
  • After

[03juan]

Possibly needs documentation changes to README?

[03juan]

I agree about the documentation, this is an implementation detail.

[Iron-E]

Thanks for the contribution!