Introduce ANSWER_PHONE_CALLS permission

This exposes an API to answer a ringing call, as well as a corresponding
runtime permission and appop

Test: Grant the permission and ensure the call gets answered.
Deny the permission, and ensure that the API call throws an exception.
Bug: 30932767
Change-Id: I4c33fcea6b95a30469fa6c0c37090be32b0ad52e
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index b3ae891..9df0954 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -895,6 +895,17 @@
         android:description="@string/permdesc_processOutgoingCalls"
         android:protectionLevel="dangerous" />
 
+
+    <!-- Allows the app to answer an incoming phone call.
+         <p>Protection level: dangerous
+    -->
+    <permission android:name="android.permission.ANSWER_PHONE_CALLS"
+        android:permissionGroup="android.permission-group.PHONE"
+        android:label="@string/permlab_answerPhoneCalls"
+        android:description="@string/permdesc_answerPhoneCalls"
+        android:protectionLevel="dangerous" />
+
+
     <!-- ====================================================================== -->
     <!-- Permissions for accessing the device microphone                        -->
     <!-- ====================================================================== -->