m <apex_name>-deps-info prints the internal/external deps of the APEX

We need to have a way to see the list of modules that directly or
indirectly contribute to an APEX. People find it difficult to determine
whether a module is included in which APEXes because APEX tracks
indirect dependencies as well as direct dependencies. Therefore, just
looking at Android.bp for the APEX itself doesn't give the answer.

This change adds a new make target <apex_name>-deps-info, which
generates out/soong/<apex_name>-deps-info.txt file that shows the
internal and external dependencies of the said APEX.
Here, internal means the dependencies are actually part of the
APEX, while external means the dependencies are still external to the
APEX.

Bug: 146323213
Test: m (apex_test amended)
Change-Id: I33d1ccf5d1ca335d71cd6ced0f5f66b8c3886d13