Wait for the disconnection of ePDN after VoNR fails

EmergencyCallDomainSelector waits for the disconnection of ePDN
before requesting network scan after VoNR fails.

Replace EmergencyCallbackModeHelper with DataConnectionStateHelper,
and make DataConnectionStateHelper inform the state of ePDN
to the EmergencyCallDomainSelector.

Bug: 330299585
Test: atest EmergencyCallDomainSelectorTest
Change-Id: I6df56793705252f577265a8062201b3e3d8009fe
7 files changed