Add a mechanism by which a factory can declare "instant failure" for
a request - which would result in it getting an OnUnavailable()
(even without a timeout).
Factories may only do this iff:
1. They know they are the only factory which may fulfill this
request (common for transport-specific requests).
2. The know that the request can definitely not be
fulfilled at any point in the future.
Bug: 31382922
Test: atest ConnectivityServiceTest
Change-Id: I9bce0f4d85fa8cad7f8a9998819f945b778c5ac5
4ad1b9f839