Watch parent directories on Windows

[smashwilson]

When a directory is watched on Windows, implicitly create non-recursive watchers the whole way up the directory tree to the drive root. When any directory along the way is removed or renamed, emit a synthetic { "action": "removed", "kind": "directory", "path": "/root" } event for the watch root and uninstall it.

[smashwilson]

This introduces a lot of native crashes for me, which is concerning because it only touches JavaScript. I haven't been able to figure out why, though: I'm seeing different crashes when I change any of the logging or run under WinDbg, and I can't seem to replicate without this commit.

I'm going to leave this unresolved for now and see how we're doing on Linux, and have another look post-:baby:.