Add tests for PAC proxies. am: 58f949afcf

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/23609479

Change-Id: I7e22c0f635ebad9e10193fa57814047ad3f4c9d5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>