Expose RPC methods to adopt and drop shell permission.

This is used by Wi-Fi connection tests to make sure the WiFi selection
dialog will always pop up.

Bug: 427467662
Test: https://paste.googleplex.com/6534052953456640 (Tested 2 RPCs locally)
Test: http://sponge2/0abe7411-5038-4250-9a84-c5ac2b5aa195 (The expected dialog poped up in connection tests)
Test: http://sponge2/ab6decba-22f9-4090-878f-1b6293bda569 (Does not break Direct tests)
Test: http://sponge2/83f5eda6-e37b-4133-8a47-ed3d0189ae36 (Does not break SoftAp tests)
Test: http://sponge2/ab6decba-22f9-4090-878f-1b6293bda569 (Does not break Aware tests)
Flag: TEST_ONLY
Change-Id: I36cff96fc163de0fc96c13138e688cfa86333703
3 files changed