File-watcher listening on gitignored files on Linux

[altsem]

Originally posted by @altsem in https://github.com/altsem/gitu/issues/437#issuecomment-3417924320

The file-watcher utilizes inotify on Linux, using the "notify" crate. Afaik, this implementation needs to traverse the entire file tree and register a listener on each file. Then whenever a change is detected, it passes through the filter we've written to check whether it should be ignored or not.

The problem is that just registering these listeners on each file takes a significant amount of time.