java_sdk_library: Expose implementation within APEX

Access to the implementation JARs is restricted to avoid code from
depending on implementation details that could change from one release
to the next which could cause compatibility issues. That is not a
problem when referenced from within the APEX that contains the
java_sdk_library.

As references from within the same APEX often need to access
implementation specific details of the java_sdk_library and doing that
from within the same APEX is safe this change all references to a
java_sdk_library made within the same APEX to use the implementation
jars instead of stub jars.

Bug: 155164730
Test: m droid
Change-Id: If239059690de61683c2ad2d8a0ce2e47286a3637
(cherry picked from commit 9b879594)