Send ACTION_EMERGENCY_CALL_STATE_CHANGED

Per carrier configuration, send the emergency call state
to exit Mobile Hotspot mode when starting emergency calls.

Bug: 328392053
Test: atest EmergencyStateTrackerTest
Manual test:
Step 1. Turn on Mobile Hotspot
Step 2. Dial 911
Step 3. Verify that Mobile Hotspot is turned off

Change-Id: I6ed1729ac3329ac18f235995bc67d85fc0c4da6f