Add mediaroutertest to frameworks/base/media/TEST_MAPPING This is a cherrypick of commit da497e609cc81d840ba5c46506be0a823b138646. Bug: 232812007 Change-Id: I283df974d80e61cdf6997b8f58c2ff9e642961d5 Merged-In: I283df974d80e61cdf6997b8f58c2ff9e642961d5 Test: N/A. TEST_MAPPING change.