IComposerClient wrapper for VTS tests

A wrapper helps with implementation details of IComposerClient and
improves re-usability with readback and base tests.

BUG: 199413815

Test: atest VtsHalGraphicsComposer3_TargetTest
Change-Id: I627748d1c779eaacf92ff6fb5ccf3138a3024681
8 files changed