IMS: Support for IMS Registration  error codes

- Add support for propagation of IMS Registration errors
- Add reason type - operator specific
- Add call drop reason type and error code CD-04 that specifies there was no
  qualified LTE network to handover to from a wifi call

Change-Id: Ib9c93dfafe8d8fbdece3a5daf6fd13ef0c16f158
2 files changed