watcher - emit URI instead of string for faster fsPath compute (for #194341)

[bpasero]

Not only do we now emit Uri from the watcher (or more specifically: UriComponents), but we will also have .fsPath computed in the watcher process. This is because each event goes through the coalescing process:

vscode/src/vs/platform/files/common/watcher.ts

Lines 318 to 324 in 7ca0b35

	private toKey(event: IDiskFileChange): string {
	if (isLinux) {
	return event.resource.fsPath;
	}
	return event.resource.fsPath.toLowerCase(); // normalise to file system case sensitivity
	}

fyi @jrieken