SDV: Create CS2A and trunk_staging release config

As part of the Open Sourcing efforts for SDV we are creating the
location for SDV's public release configs here. The idea is to have
these release flags separate from the Core Android flags to not add
additional (on these platforms) unused flags.

Bug: 470340912
Test: lunch sdv_core_cf-trunk_staging/cs2a-userdebug && m
Test: all_aconfig_declarations succeeds
Change-Id: Icb1379b610eb598cf26c0e8d25d42df2e0a979ac