Fix the forwarded number can't be displayed on in-call UI

Extras of ImsCallProfile is purposefully restricted to simple objects
that can be safely be persisted to and restored from disk in order to
sending data between processes.
We need to handle ImsCallProfile.EXTRA_FORWARDED_NUMBER data as
string array not string array list.

Test: manual
Test: auto - Passed FrameworksTelephonyTests
Bug: 203856193

Change-Id: I3997304d52d01b2ebc931c1df9afb356dfd20465