Add new stub_only_static_libs attr for sdk_library

Allow java_sdk_libraries to include libraries statically into their
stubs. The immediate use-case of this is to embed libcore notice files
into their stubs.

Also extend the java_sdk_library tests for impl/stub-only-libs, plus
some not assert utils.

Bug: 173186484
Bug: 184839599
Test: soong tests
Change-Id: I1ebf2f35c048eab5cec5125482a0304fe660f188