Add support for SRVCC during a ringing call

1. When checking for more than one ringing call, if the multiple
ringing calls are due to SRVCC, i.e having the same address then
do not disconnect the ringing call on CS.

Change-Id: Id3aa7e24f54cedcea6eb340742efdd2f531156ce
CRs-Fixed: 539111
Merge "Add support for SRVCC during a ringing call"
telephony: Add Explicit Call Transfer (ECT) feature

Use ECT as "4 + Send".

Bug: 9745857
Change-Id: If94d7ad33eb72dede86030c26e8a8c1b5b8125e3
Merge "telephony: Add Explicit Call Transfer (ECT) feature"
Merge remote-tracking branch 'caf/jb_mr2' into caf