[mobile] Device-based emergency call capable

This is (yet another) departure from the legacy logic to answer the
question "can the device make emergency calls". This is strictly
separate from the calculation of a per-subscription understanding of
emergency call capability.

We listen for any SERVICE_STATE broadcasts that don't refer to a known
subscription (this part is done by checking subId = -1, and assumes
that -1 in this case means "device-based" rather than "carrier-based").
When that happens, we call the new telephony APIs for getting the number
of slots, and subsequently querying each slot for its service state.

If any service state for a given slot reports that it is capable of
emergency calls, then the top-level connections repository reports it.
And we can use that in our logic downstream (e.g. for satellite)

Test: MobileConnectionsRepositoryTest
Test: MobileIconsInteractorTest
Bug: 346579914
Flag: NONE bugfix
Change-Id: Id0f74df979fcd947e0fd856add9c38a764b56b3b