typing: disable a few incorrect warnings in pywatchman The module-attr warnings are for things that only exist on Windows, and the wrong-keyword-args warning is due to a special case for a specific constructor. Both of these are properly conditionalized.

watchman: refactor transport connecting to unconfuse pytype Pytype sees `self.proc` as potentially `None` here, even though it's set by the `_connect()` logic. Instead of asserting, simply use the process returned by that method (which it sets into `self.proc` before returning, so there's no functional change here).

watchman: refactor `ctypes.windll.kernel32` references to a local variable This is flagged by pytype as an attribute-error, and it's easier to disable that in a single place.