compat/fsmonitor/fsm-listen-win32: implement FSMonitor backend on Windows

Teach the win32 backend to register a watch on the working tree
root directory (recursively).  Also watch the <gitdir> if it is
not inside the working tree.  And to collect path change notifications
into batches and publish.

Signed-off-by: Jeff Hostetler <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: jeffhostetler