Merge "Implementation of IMS registration management APIs for SipTransport" am: 71a1997ce3 am: 6ab064feba

Original change: https://android-review.googlesource.com/c/platform/packages/services/Telephony/+/1527158

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Iabcdc35fa748d55236878f962db8d2497b356f13