Expose various Telecom constants

Expose constants in Telecom that are being used in Telephony.
Note -- nothing is exposed here -- it's a modified cherry pick from
internal where all the APIs have been rehidden.

Bug: 146834818
Test: NA
Change-Id: Ib5cf76183edced3eeffbca87a7c980a85288f937
Merged-In: Ib5cf76183edced3eeffbca87a7c980a85288f937