Move TelephonyCapabilities from Phone to telephony

- Move the class.
- Remove some TODOs mentioning this action : the class should belong to
  telephony layer instead of to the Phone package
- Add private strings used in the class

Bug: 6252254
Change-Id: I0d4ca2f8e4d775004d146fe6f9c60165a94366a9
3 files changed