Switch framework-sdkextensions to use java_sdk_library

The names of the individual modules do not quite follow the pattern
that java_sdk_library uses so this temporarily sets the following:
    naming_scheme: "frameworks-modules"

That causes java_sdk_library to use a naming scheme that matches the
one used by the individual modules of this. It will be cleaned up
later.

Test: Removed API from current.txt, ran checkapi and it detected the
      API change. Ran update-api and it updated the API txt file.
      Added method without any nullability info, ran checkapi and API
      lint reported issues as expected.
Bug: 155164730
Change-Id: Ifcdbfd77373710481343c9ff800543eaaa8c2ea8