Enable group calls without video and audio track by configuration of MatrixClient (#3162)

* groupCall: add configuration param to allow no audio and no camera

* groupCall: enable datachannel to do no media group calls

* groupCall: changed call no media property as object property

* groupCall: fix existing unit tests

* groupCall: remove not needed flag

* groupCall: rename property to allow no media calls

* groupCall: mute unmute even without device

* groupCall: switch to promise callbacks

* groupCall: switch to try catch

* test: filter dummy code from coverage

* test: extend media mute tests

* groupCall: move permission check to device handler

* mediaHandler: add error in log statement

src/client.ts

@@ -371,6 +371,13 @@ export interface ICreateClientOpts {
      * Defaults to a built-in English handler with basic pluralisation.
      */
     roomNameGenerator?: (roomId: string, state: RoomNameState) => string | null;
+
+    /**
+     * If true, participant can join group call without video and audio this has to be allowed. By default, a local
+     * media stream is needed to establish a group call.
+     * Default: false.
+     */
+    isVoipWithNoMediaAllowed?: boolean;
 }
 
 export interface IMatrixClientCreateOpts extends ICreateClientOpts {
@@ -1169,6 +1176,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
     public iceCandidatePoolSize = 0; // XXX: Intended private, used in code.
     public idBaseUrl?: string;
     public baseUrl: string;
+    public readonly isVoipWithNoMediaAllowed;
 
     // Note: these are all `protected` to let downstream consumers make mistakes if they want to.
     // We don't technically support this usage, but have reasons to do this.
@@ -1313,6 +1321,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         this.iceCandidatePoolSize = opts.iceCandidatePoolSize === undefined ? 0 : opts.iceCandidatePoolSize;
         this.supportsCallTransfer = opts.supportsCallTransfer || false;
         this.fallbackICEServerAllowed = opts.fallbackICEServerAllowed || false;
+        this.isVoipWithNoMediaAllowed = opts.isVoipWithNoMediaAllowed || false;
 
         if (opts.useE2eForGroupCall !== undefined) this.useE2eForGroupCall = opts.useE2eForGroupCall;
 
@@ -1880,14 +1889,17 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
             throw new Error(`Cannot find room ${roomId}`);
         }
 
+        // Because without Media section a WebRTC connection is not possible, so need a RTCDataChannel to set up a
+        // no media WebRTC connection anyway.
         return new GroupCall(
             this,
             room,
             type,
             isPtt,
             intent,
+            this.isVoipWithNoMediaAllowed,
             undefined,
-            dataChannelsEnabled,
+            dataChannelsEnabled || this.isVoipWithNoMediaAllowed,
             dataChannelOptions,
         ).create();
     }