Match LiveKit participants against all backend identities

A member authenticated through the legacy JWT endpoint publishes under a
`user:device` identity, while one authenticated through the default
endpoint publishes under a hashed identity. Both are listed in the
membership's backend identities, so match against the whole list rather
than only the primary one.

src/state/CallViewModel/remoteMembers/MatrixLivekitMembers.ts

@@ -111,8 +111,8 @@ export function createRemoteMatrixLivekitMembers$({
             const participants = transport
               ? managerData.getParticipantsForTransport(transport)
               : [];
-            const matches = participants.filter(
-              (p) => p.identity == membership.rtcBackendIdentity,
+            const matches = participants.filter((p) =>
+              membership.backendIdentities.includes(p.identity),
             );
             const participant = matches[0] ?? null;
             const connection = transport