pom2mk to include extra-deps as top-level deps too

Specifically, the use case is android-support-car requires some stubs that don't have a Maven pom.
So those stubs can't easily be listed as a dependency in the pom.
However, we do want the dependency to exist when importing to Make and detected by extract_deps.py

Bug: 76692459
Test: m -j blueprint_tools \
      && update_prebuilts.py -s <build_id> \
      && git diff HEAD^ -- fix_dependencies.mk \
      && m -j checkbuild

Change-Id: If546ecf7416580a01bde7b906976ada4b1145253