Refactor the OptimizedBuildTarget base class to more simply handle
enabling/disabling build optimizations based on flags. Now all
optimizers (aside from the no-op NullOptimizer will have their enabling
built into the base class, and also necessitate their get_build_targets
and package_outputs functions to be defined in order to not error out.
Add the GeneralTestsOptimizer class as well, unimplemented for now.
Test: atest build_test_suites_test
Bug: 358215235
Change-Id: Ide22c64fc238d754db8d8e76484947401e54e680
Add functionality in build_test_suites.py to not build targets if
their outputs are not used in the test configurations saved in the build
context. If none of the tests reference the targets' outputs they will
not be built at all.
Note that the corresponding flags will need to be enabled for these
optimizations to take place.
Test: atest optimized_targets_test
Bug: 348489774
Change-Id: I8f0ac90e75552ae80073f13229b026c7f23476a6
