Distinguish between integration test and other tests

This change tries to distinguish between the preparations needed for an
integration test and the preparations needed for more unit-testy tests.

Integration tests exercise most, if not all of Soong (at least the
parts that are available when running tests in a specific package) and
as a result can take a long time. Other tests, while being as realistic
as possible, should only use a subset of the preparations in order to
reduce run time.

Registering module types has very little overhead so it is simplest to
try and register those all together. However, care needs to be taken
for singletons and mutators as they can do a lot of work. Especially
with tests that include lots of default module definitions such as are
created by java.GatherRequiredDepsForTest().

Once it is possible to use test fixtures in tests it will be much
easier to customize tests individually and so avoid just adding new
test specific content to the common deps.

Bug: 181070625
Test: m nothing
Change-Id: Ia0a676297224d90df947054746e7f99563ffb323