Add handover permission, fill in some missing API gaps.

Adding the ACCEPT_HANDOVER runtime permission which an app must have in
order to accept handovers (this is per design).

Adding missing onHandoverComplete method in the android.telecom.Connection
API (per design).

Finishing plumbing for android.telecom.Call#onHandoverComplete API.

Fix issue where the new handover API methods would never get called; the
legacy handover extra was being used in this case when it should not have
been.

Bug: 65415068
Test: Verified using new CTS tests
Change-Id: If1558f6a23911862c02ac5b18fb62d86911ed7e2
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index ea791a5..0861e710 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -971,6 +971,23 @@
                 android:description="@string/permdesc_manageOwnCalls"
                 android:protectionLevel="normal" />
 
+    <!-- Allows a calling app to continue a call which was started in another app.  An example is a
+         video calling app that wants to continue a voice call on the user's mobile network.<p>
+         When the handover of a call from one app to another takes place, there are two devices
+         which are involved in the handover; the initiating and receiving devices.  The initiating
+         device is where the request to handover the call was started, and the receiving device is
+         where the handover request is confirmed by the other party.<p>
+         This permission protects access to the
+         {@link android.telecom.TelecomManager#acceptHandover(Uri, int, PhoneAccountHandle)} which
+         the receiving side of the handover uses to accept a handover.
+         <p>Protection level: dangerous
+    -->
+    <permission android:name="android.permission.ACCEPT_HANDOVER"
+                android:permissionGroup="android.permission-group.PHONE"
+                android.label="@string/permlab_acceptHandover"
+                android:description="@string/permdesc_acceptHandovers"
+                android:protectionLevel="dangerous" />
+
     <!-- ====================================================================== -->
     <!-- Permissions for accessing the device microphone                        -->
     <!-- ====================================================================== -->