fix oem_XXXX ids to incorporate both ranges

The XXXX now lines up to the underlying uid and has no offset.
Work with AID_OEM_RESERVED uids.

Test uses hard coded values to catch changes in the API expectations
that may occur in private/android_filesystem_config.h.

SideEffects: names change, some product dependencies.

Bug: 27999086
Change-Id: Ic2b4c36de74ae009a44e14711c75834293828207