Ensure target phone account is set for all conference types.

- Fixed issue where ImsConference based the phone account handle on the
ImsPhone, rather than the base Gsm/Cdma phone.
- CDMA and GSM conferences were setting phone account handle as null.

Bug: 23035408
Change-Id: Iba4b674b3fe73a8cc8e43da4af7e36f653e3772e
4 files changed