Make hidden API isDataCapable for Telephony

Rename isDataCapable to isDataConnectionEnabled as a System API for
 System UI.

Cherry-picking TelephonyManager part of ag/10063635

Test: RILTest; Treehugger; cts
Bug: 147017757
Merged-In: I96b45575eb7f030f3dcb9539c06f8ec25539e2e9
Merged-In: I19ac83f5865e8763cd9414c41d4609f79d0db164
(cherry picked from commit 29141580)

Change-Id: I96b45575eb7f030f3dcb9539c06f8ec25539e2e9