Previously, on macOS, we set the [WatchRoot
flag](https://developer.apple.com/documentation/coreservices/kfseventstreamcreateflagwatchroot)
to `FsEventStreamCreate` (via our notify fork). This causes the
resulting stream to produce an event when any segment of the watched
path changes due to a rename (e.g. `/Users/cole/zed/crates/gpui` ->
`/Users/cole/zed2/crates/gpui`).

The cost of this is that for each path we watch on macOS, we hold open
file descriptors for that path and all its parents (and these are not
deduplicated across watched paths).
This especially blows up our file descriptor usage with non-visible
worktrees from GTD jumps:


```
zed     25415 cole  721r      REG               1,14     99826           168007500 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/option.rs
zed     25415 cole  722r      DIR               1,14      2432           168008864 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src
zed     25415 cole  723r      DIR               1,14       128           168008863 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib/rustlib/src/rust/library/core
zed     25415 cole  724r      DIR               1,14       928           168008723 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib/rustlib/src/rust/library
zed     25415 cole  725r      DIR               1,14       128           168008722 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib/rustlib/src/rust
zed     25415 cole  726r      DIR               1,14        96           168008721 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib/rustlib/src
zed     25415 cole  727r      DIR               1,14       704           168004176 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib/rustlib
zed     25415 cole  728r      DIR               1,14       256           168004175 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin/lib
zed     25415 cole  729r      DIR               1,14       224           168004164 /Users/cole/.rustup/toolchains/1.97.1-aarch64-apple-darwin
zed     25415 cole  730r      DIR               1,14       576              292591 /Users/cole/.rustup/toolchains
zed     25415 cole  731r      DIR               1,14       224              292480 /Users/cole/.rustup
zed     25415 cole  732r      DIR               1,14      8576               43880 /Users/cole
zed     25415 cole  733r      DIR               1,14       160               18221 /Users
```

This PR bumps our notify dependency so that we no longer set that flag,
and instead just wake the background scanner loop every 5s to check
whether the worktree root path has changed. Note that both before and
after this change, the process_events arm of that loop checks the
worktree root path in the same way before doing anything else, so there
is no risk of descending further into the background scanner code with
an incorrect root path.

Release Notes:

- Made Zed use fewer file descriptors on macOS.