Expose active calls from in call UI

Dual SIM features need to know what phone account the current call is using because usually only one SIM can be in a call at the same time.

TEST=TAP
Bug: 69675796,72618783
Test: TAP
PiperOrigin-RevId: 194121273
Change-Id: I512eb7aca2050f38449b0a911dea9cee9b5ffdb5
13 files changed