Only expose RTC backend identity debug info where we actually use it

We only ever inspect the RTC backend identity of user media tiles. So it only needs to be exposed on the user media view model.

src/state/MediaViewModel.ts

@@ -257,7 +257,6 @@ abstract class BaseMediaViewModel {
      * The Matrix user to which this media belongs.
      */
     public readonly userId: string,
-    public readonly rtcBackendIdentity: string,
     // We don't necessarily have a participant if a user connects via MatrixRTC but not (yet) through
     // livekit.
     protected readonly participant$: Observable<
@@ -407,7 +406,10 @@ abstract class BaseUserMediaViewModel extends BaseMediaViewModel {
     scope: ObservableScope,
     id: string,
     userId: string,
-    rtcBackendIdentity: string,
+    /**
+     * The expected identity of the LiveKit participant. Exposed for debugging.
+     */
+    public readonly rtcBackendIdentity: string,
     participant$: Observable<LocalParticipant | RemoteParticipant | null>,
     encryptionSystem: EncryptionSystem,
     livekitRoom$: Behavior<LivekitRoom | undefined>,
@@ -421,7 +423,6 @@ abstract class BaseUserMediaViewModel extends BaseMediaViewModel {
       scope,
       id,
       userId,
-      rtcBackendIdentity,
       participant$,
       encryptionSystem,
       Track.Source.Microphone,
@@ -779,7 +780,6 @@ export class ScreenShareViewModel extends BaseMediaViewModel {
     scope: ObservableScope,
     id: string,
     userId: string,
-    rtcBackendIdentity: string,
     participant$: Observable<LocalParticipant | RemoteParticipant>,
     encryptionSystem: EncryptionSystem,
     livekitRoom$: Behavior<LivekitRoom | undefined>,
@@ -793,7 +793,6 @@ export class ScreenShareViewModel extends BaseMediaViewModel {
       scope,
       id,
       userId,
-      rtcBackendIdentity,
       participant$,
       encryptionSystem,
       Track.Source.ScreenShareAudio,

src/state/ScreenShare.ts

@@ -28,7 +28,6 @@ export class ScreenShare {
     private readonly scope: ObservableScope,
     id: string,
     userId: string,
-    rtcBackendIdentity: string,
     participant: LocalParticipant | RemoteParticipant,
     encryptionSystem: EncryptionSystem,
     livekitRoom$: Behavior<LivekitRoom | undefined>,
@@ -41,7 +40,6 @@ export class ScreenShare {
       this.scope,
       id,
       userId,
-      rtcBackendIdentity,
       of(participant),
       encryptionSystem,
       livekitRoom$,

src/state/UserMedia.ts

@@ -143,7 +143,6 @@ export class UserMedia {
                     scope,
                     `${this.id}:${key}`,
                     this.userId,
-                    this.rtcBackendIdentity,
                     p,
                     this.encryptionSystem,
                     this.livekitRoom$,