linux: Replace current fs::watch with PollWatcher.

[CharlesChen0823]

Follow with #11595, and comment.

1. Currently, in linux platform, using notify::recommanded_watcher for watch config.json file modify.
2. When using ctrl-shift-p toggle vim mode, will using NamedTempFile to rename with exsit file, notify will emit Modify and Delete event.
3. In current notify default impl, Delete event will triggle watcher remove watch file anymore. Only restart Zed will work for config.json modify.
4. replace with PollWatcher will not cause this problem.

But, there also leave another problem, because linux platform active_window not implement, after modify vim mode, need manual click other tab active vim mode work.

I don't know if this is accept modify.

Release Notes:

• N/A