Allow android tests to specify a mainline package name

Tests that run against mainline modules generally need to be built
twice: once for aosp (unsigned) and once for internal (signed).
The override_android_test rule is really useful for generating a
signed version of the unsigned test.

However, mainline tests need to use a MainlineTestModuleController
to only run tests on targets with the expected module. Since unsigned
and signed mainline modules have different package names, this means
the test config needs to be updated when overriding a test.

Add a new "mainline_package_name" argument so that android test rules
can update the targeted mainline package. Without this, the only way
to create a mainline package test is to instead use android_test, which
results in a lot of copy-pasta.

Test: added tests to soong
Test: manual, using a locally-modified RkpdAppUnitTest
Test: test_config_fixer_test.py
Change-Id: Idaffd63f225719a2bfda41018fda630b17db0080