Add call button

lib/ui/screens/group_sections/group_conversation_section.dart

@@ -25,11 +25,22 @@ class GroupConversationSection extends StatelessWidget {
           ),
           Positioned(
             right: 1.0,
-            child: IconButton(
+            child: Row(
+              children: [
+                conv.callCapabilities != CallCapabilities.NONE
+                    ? IconButton(
+                        icon: Icon(Icons.phone),
+                        onPressed: () =>
+                            MainController.of(context).startCall(conv.id),
+                      )
+                    : Container(),
+                IconButton(
                   icon: Icon(Icons.settings),
                   onPressed: () => MainController.of(context)
                       .openConversationSettingsRoute(conv),
                 ),
+              ],
+            ),
           )
         ],
       );