Separate out lists of modules from build rules

This simplifies management of the build rules across different branches
that may have different lists of modules.

Additionally, we dedupe the list of module system stubs.

Bug: 184839225
Test: m
Merged-In: Ibef1fb686305b5b1b50811b7d1c6d677d07d7177
Change-Id: Ibef1fb686305b5b1b50811b7d1c6d677d07d7177