Introduce OverrideRequest type property

Adding a property to denote what type of
OverrideRequest is being made, allows us
to provide different behaviors depending
on if the request is to override the
emulated state of the device or the base
state.

Bug: 234336979
Test: OverrideRequestControllerTest
Change-Id: I63fb6c040c8a7116d18657e5cb041b5f67a7fb90