Add rs-notify implementation of fs::watch (#9040)

This PR simplifies the Zed file system abstraction and implements
`Fs::watch` for linux and windows.

TODO:
- [x] Figure out why this fails to initialize the file watchers when we
have to initialize the config directory paths, but succeeds on
subsequent runs.
- [x] Fix macOS dependencies on old fsevents::Event crate

Release Notes:

- N/A

crates/gpui/src/platform/linux/platform.rs

@@ -324,7 +324,7 @@ impl Platform for LinuxPlatform {
         })
     }
 
-    //TODO linux
+    //todo(linux)
     fn app_path(&self) -> Result<PathBuf> {
         Err(anyhow::Error::msg(
             "Platform<LinuxPlatform>::app_path is not implemented yet",
@@ -338,7 +338,7 @@ impl Platform for LinuxPlatform {
         UtcOffset::UTC
     }
 
-    //TODO linux
+    //todo(linux)
     fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
         Err(anyhow::Error::msg(
             "Platform<LinuxPlatform>::path_for_auxiliary_executable is not implemented yet",
@@ -390,8 +390,7 @@ impl Platform for LinuxPlatform {
         })
     }
 
-    //TODO linux: add trait methods for accessing the primary selection
-
+    //todo(linux): add trait methods for accessing the primary selection
     fn read_credentials(&self, url: &str) -> Task<Result<Option<(String, Vec<u8>)>>> {
         let url = url.to_string();
         self.background_executor().spawn(async move {

crates/gpui/src/platform/linux/wayland/client.rs

@@ -281,7 +281,7 @@ impl Client for WaylandClient {
             CursorStyle::ResizeUp => "n-resize".to_string(),
             CursorStyle::ResizeDown => "s-resize".to_string(),
             CursorStyle::ResizeUpDown => "ns-resize".to_string(),
-            CursorStyle::DisappearingItem => "grabbing".to_string(), // TODO linux - couldn't find equivalent icon in linux
+            CursorStyle::DisappearingItem => "grabbing".to_string(), // todo(linux) - couldn't find equivalent icon in linux
             CursorStyle::IBeamCursorForVerticalLayout => "vertical-text".to_string(),
             CursorStyle::OperationNotAllowed => "not-allowed".to_string(),
             CursorStyle::DragLink => "dnd-link".to_string(),

crates/gpui/src/platform/linux/x11/client.rs

@@ -361,7 +361,7 @@ impl Client for X11Client {
         Box::new(X11Window(window_ptr))
     }
 
-    // TODO linux
+    //todo(linux)
     fn set_cursor_style(&self, _style: CursorStyle) {}
 
     fn get_clipboard(&self) -> Rc<RefCell<dyn ClipboardProvider>> {