Allow Soong to autogenerate test configs

Move the configuration for autogenerating test configs into Soong,
and add LOCAL_FULL_TEST_CONFIG so that Soong can specify the full
path to a generated test config.

Also add a java junit test config template.

Bug: 70770641
Test: m checkbuild
Test: atest CtsUiRenderingTestCases
Test: atest junit-params-test
Change-Id: I2e64bc33c949ab7b342be518f94a81a186fe9c07