Bp2Build converter for android_library_import and android_library.

Minor refactor of android_app converted to account for common attributes
between library and app.

Test: go test
Test: ../bazel/ci/bp2build.sh
Change-Id: I60b06eef6d2b9bc2d91f8b83522747ebbe76bbb6
Bug: 215230093
Bug: 215230095