Add SIP configration Bundle keys for UA and CNI

Adds IMS SIP configuration bundle keys for User-Agent and
Cellular-Network-Info headers required by some networks.

Bug: 178606181
Test: atest CtsTelephonyTestCases:SipDelegateManagerTest
Change-Id: I389162ca0c6348580f6ee8bb6ce5ee3a4e84595e