Add exclude_from_vendor_snapshot property, related logic

When building a vendor snapshot, the general rule the
build system uses to select a module for inclusion into
the vendor snapshot is if it's a framework module.
However, there are cases where a partner may modify the
framework module, thereby assuming control of that
module.

This change adds the exclude_from_vendor_snapshot
property allowing the partner to mark a module that
would normally be included in the vendor snapshot for
exclusion. This module is then built from source when
building the vendor image against the vendor snapshot.

Bug: 165705527
Test: m nothing
Test: build partner code against vendor snapshot
Change-Id: I6c5c15f13eeeb8f29717a4abd84b65fa72096889