Rename VoLTE/WFC enable API to available - add VT available API.

Renamed API to use consistent semantics: available refers to the current
state of the service rather then whether feature is enabled by device/carrier/
user.

Added VT API to match VoLTE/WFC.

Change-Id: Ia2ed60bc88c6ac58e6cdab7e2eb31d383440c949
diff --git a/src/com/android/phone/PhoneInterfaceManager.java b/src/com/android/phone/PhoneInterfaceManager.java
index 0e82b99..d65d875 100644
--- a/src/com/android/phone/PhoneInterfaceManager.java
+++ b/src/com/android/phone/PhoneInterfaceManager.java
@@ -2639,7 +2639,7 @@
      * {@hide}
      * Returns the IMS Registration Status
      */
-    public boolean isWifiCallingEnabled() {
+    public boolean isWifiCallingAvailable() {
         return mPhone.isWifiCallingEnabled();
     }
 
@@ -2647,10 +2647,17 @@
      * {@hide}
      * Returns the IMS Registration Status
      */
-    public boolean isVolteEnabled() {
+    public boolean isVolteAvailable() {
         return mPhone.isVolteEnabled();
     }
 
+    /*
+     * {@hide} Returns the IMS Registration Status
+     */
+    public boolean isVideoTelephonyAvailable() {
+        return mPhone.isVideoEnabled();
+    }
+
     private boolean canReadPhoneState(String callingPackage, String message) {
         try {
             mApp.enforceCallingOrSelfPermission(