product: Mainline wifi module

Move wifi services into a separate APK.

For now, the wifi stack will run inside system_server for all devices.

In the future, when the wifi stack becomes a mainline module:
For regular devices, the wifi stack will be loaded into
the network stack process - WifiStack.apk.
For GO (low memory) devices, the wifi stack will be always
loaded into system_server - InProcessWifiStack.apk.

Bug: 113174748
Change-Id: I1a272cbbb6a5284850177db41ec27a6f6035bb03