Create all variants of stubs for wifi

Add separate publicapi, systemapi and module_libs stubs for wifi, and
use a naming scheme consistent with other modules.

Bug: 147768409
Test: m
Test: m framework-wifi-stubs-{public,system,module_libs_}api
Change-Id: I8b606c440f76349f2406b72c23e3f67b6378d385