Add test suite handling to central androidmk code

MTS is introducing partial MTS test suites that are per-module, with
names of the format: mts-${MODULE}. By centralizing the code for test
suites, we can automatically add "mts" test suite when an
"mts-${MODULE}" test suite is specified, reducing duplication.

Test: m mts
Bug: 170318013
Change-Id: I8ce9d3c252fcc0a937bb5f2826d21cb6c6932d82