Perform camera permission and app ops check when setting camera for VT.

When a calling InCallService attempts to use the setCamera API on the
VideoCall, Telecom will perform a permission check to ensure that the
caller has the correct camera permission and passes the app-ops camera
check.  A failure to set the camera will result in a callback via the
call session event API.

This got a little messy as the app ops package name needs to come from the
InCallService, and handler usage in the VideoProvider API means we had to
pass around the uid/pid of the caller, obtained before we trampoline onto
the handler.

Test: Unit tests added, plus manual tests.
Bug: 32747443
Change-Id: Ib96114502fe459b0429a87c5d13640b68ae6a2f7