Add @SystemApi(MODULE_LIBS) mainline stub in runtime

- It turned out the stub jar we use doesn't contain
MODULE_LIBS APIs.

- There's another jar containing that, so add that to classpath.

- However, the new one doesn't contain libcore APIs, so we still
need to keep the original jar.

- The new jar need to come before the original one, but unfortunately
CleanSpec.mk may not be working now, so instead of renaming the existing
one, let's give this weird name to the new one.

Fix: 416335279
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh -s
Test: manual test looking at the newly added jar
Flag: EXEMPT host test change only
Change-Id: I10986d5e20dd4efd0d2d2568c0847fc9f7efd025