Hide/show Telephony video setting according to if IMS is enabled.

+ Add utility function get this value in ImsUtil.
+ Check this value to show/hide setting in Call Settings.
+ Include flag to override behavior and always hide VT, since it's
not shipping in MR1.
+ Take this account when reporting when the phone interface manager
reports whether we can make video calls.

Bug: 16014284
Change-Id: I31a13da61820988cdb53159126c6be9478b6a583
3 files changed