Add a new UID range for supplemental processes.

These are processes that are spawned alongside regular app processes.
They have their own UID range, such that they can be properly isolated
from applications.

Add some APIs in Process that allows the system and mainline
modules to verify that a particular UID belongs to a supplemental
process, and to map between the supplemental process and the
corresponding app process.

Bug: 215012578
Test: N/A
Change-Id: I02aaaa1c2bcf9d141ddc97747eb6d7edd52d7b92