IMS-VT: Propagate video capability of phone to telecomm.

To dynamcally enable/disable Make Video Call button in dialer,
the phone capabilities need to be propagate to TelecommMgr.
Propagate video capability of phone to telecomm layer.

IMS-VT: Notify call updates
-When call type is updated from VoLTE to VT, this notification
 does not reach UI. Fix this

Fix the issue - Unable to add second VT call when first call is active
- Cache the video state of the new pending call when the foreground
  call is HOLDING.
- Use the cached video state when dialing the pending MO call or
  accepting the pending MT call after the first call is put on HOLD.

Ims: Add support for WIFI network mode notifications
Added support for enabling and disabling features for Voice and
Video when network mode is WIFI or IWLAN

IMS-VT: Peer capabilities
-Add support for peer capabilities
Change-Id: I44177dd6804b69a7b790021502eda0eb3bea3cab

IMS-VT: Do not allow changing the TTY mode during a Video call
When the device is already in a video call, the user SHOULD NOT
be allowed to change the TTY mode. If the user tries to change,
then an UI alert message will be displayed explaining it cannot
be changed during video calls.

Propagate the call substate changed message to the UI

Notify video capability to listeners in certain new scenarios
- In certain cases, we have seen that when the phone
  object is deleted/re-created, we fail to notify the
  video capability to the listeners.
- There also seemed to be a race condition when the
  time a listener registers is not in sync with
  the time we are notified of the video capability.
- In order to fix the above two issues, we notify
  registrants when a new phone is created and
  updateParentPhone is called. Also, when a new
  registrant registers with us for video capability
  changed, we immediately notify them of our cached
  capability.

Change-Id: Ic6002c2518104c20b5de10d1081af4559f506ace

IMS-VT: Enable Video conferencing.
Enable Video conferencing.

Change-Id: Ia1155960492165cff7f4993a4bf98ecc920ebf41