refactor: introduce fzf-lua as an alternative of telescope.

[ayamir]

This pr introduce fzf-lua as fuzzy searcher to replace part functionalies of telescope.nvim to achieve higher performance when search in a big repo. I forked and rewrote search.nvim to make it support fzf-lua. Not all pickers are equivalent such as frecency and not all pickers are replaced, but now it basically works. It will close #1463.

output.mp4

@Elite-zx You can try it now.

[misumisumi]

The search box in fzf-lua unintentionally becomes bottom when I merged it into feat/ai-chat in my environment.
This is because codecompanion.nvim calls telescope first in https://github.com/olimorris/codecompanion.nvim/blob/34d45b0790719e6c5b437d609cf583f87a4e2edb/lua/codecompanion/providers/init.lua#L3C1-L15C4 (telescope's default position is "bottom")
I replaced telescope with fzf-lua and the problem disappeared.
Hmm. Including both telescope.nvim and fzf-lua may result in unintended conflicts, so you might need to be a bit cautious.

[ayamir]

telescope's default position is "bottom"

I made the prompt position setting of telescope as default.

[charliie-dev]

sorry, recently i got very busy. i might not have time to review the PRs. 😥

[ayamir]

Finally, I chose to use fzf for searching as a configurable option for the following reasons:

1. telescope is sufficient for most situations
2. fzf requires additional binary dependencies, and because it uses multiple processes, it starts slower than telescope when the system load is high.

Could you review it when you have time? @misumisumi @Elite-zx