Add two tests for Stable AIDL composer3 as a start of tests.

If service exists then we can proceed with test otherwise we skip tests

This should help us write all the tests until we have the service implementation.

Test: atest VtsHalGraphicsComposer3_TargetTest Tests don't just work yet, we don't have service implemented yet.
BUG: 202053621
Change-Id: Ia9506dada0f1b5da446d6e2086aa4534c60d5565