Implement node-module add-on for native Windows file watching

Fixes issue #6551- "[File Watchers] Can not externally rename a directory with subfolders on Windows"

Requires associated [pull request #413](https://github.com/adobe/brackets-shell/pull/413) from brackets-shell repo.

Replace the previous, node-based fs.watch() implementation with a new, Windows-specific node-module.  In the previous implementation, node's fs.watch() doesn't (yet) support the recursive subfolder flag of ReadDirectoryChangesW().  With the new, native C++ node add-on, we can now support this recursive mode, and only have to set a single watcher on the entire project tree.

BTW, this has the added benefit of actually "locking" the root of the project folder tree so that it can't be deleted/renamed out from underneath Brackets too.

NOTE: this pull request against the `release` branch replaces the earlier PR #6673 against `master`.  Also, I've squashed the commits for readability.