Allow call forwarding number with prefixes to be dialed while on IMS roaming

If the carrier supports call forwarding number prefixes to be allowed
while on IMS roaming, then the number should be dialed and forwarded successfully

Bug: 153413483
Test: Verify the call using *72 <number to be forwarded to> is dialed and forwarded successully
Change-Id: Ia93dec2ebb11aa3ab8f48975a9b6f02089d1482b