Add individual API tracking files for modules

This adds metalava api tracking generation to the module
stub rules, to make sure we know exactly what API a
particular module stub exports.

Bug: 147768409
Test: m update-api
Exempt-From-Owner-Approval: Approved in master
Change-Id: Iaf2ef5b5751eb208d119ddbc74481239366fe581
Merged-In: Iaf2ef5b5751eb208d119ddbc74481239366fe581