1. Added two new API for screen state replacement.
2. Data call API refactoring work.
bug: 20125037, 32224135, 32223897, 32249926, 30282096, 30173958,
33653220
Test: Telephony sanity tests and unit tests
Merged-In: I6b266637914a85bd57c6a055c52c8ff4ced17e1f
Change-Id: I342b99bed8663d107052e791ac97949b34f7dd99
+ Opened new bug b/34683858 for addressing one of the TODO in P.
Bug: 34109705
Test: Removed only comments.
Change-Id: Ie78eacbc80def2df3ec448f14a89fbac185bf2af