Add uid/package check in WifiServiceImpl#getConfiguredNetworks

Enforce UID to package name check to validate that the caller isn't
providing a fake packageName which isn't their own.

Bug: 197749180
Test: atest com.android.server.wifi
Change-Id: Ia8530b0b8de8de87932844439bb56da43aef4387
(cherry picked from commit 7d8276552fab89d27ca496031dbb94950e75d6a6)