RIL: Support SMS over IMS

RIL: Support SMS over IMS

RIL_REQUEST_IMS_REGISTRATION_STATE is used to aquire IMS registration state.
RIL_UNSOL_RESPONSE_IMS_NETWORK_STATE_CHANGED is called when IMS registration
state has changed.
RIL_REQUEST_IMS_SEND_SMS is used to send MO SMS over IMS. However, if retry
field is set in case of failure, RIL_REQUEST_IMS_SEND_SMS sets messageRef from
RIL_SMS_RESPONSE of corresponding failed MO SMS, and sets retry field to
non-zero. If voice is available, sends RIL_REQUEST_IMS_SEND_SMS retries with
data encoded based on voice tech available.

Bug: 9626411

Change-Id: If0ecc9fa47661f6560171e472f3c464713e97968