Add @RequiresApi to new APIs for Coex

Annotated Coex APIs and classes with @RequiresApi for S, and added the
appropriate SdkLevel checks. Removed the remaining coex exceptions from
the lint baseline.

Bug: 186908464
Bug: 181358771
Test: m lint-check

Change-Id: I736365da26226c6d6baa76666f4850d0e4f9a42b
7 files changed