Moves IMS Emergency Calling state

The IMS Emergency Calling availability state
used to be stored in the ImsServiceController and
polled when needed. This change moves the
state to MmTelFeatureConnection via an update.

By moving it here, we can reduce the number of
calls through TelephonyManager and support
MSIM.

Bug: 74389647
Test: Telephony Unit Tests, Telephony Test ImsService app
Change-Id: I35ff8723afff2e69ab36e6e99c2efd5ae7a4868a