Identify transports by server name as well as URLs

A transport with only a LiveKit SFU `url` has to be authenticated through
our own homeserver, which needs to know the name of the server owning the
SFU. Carry that name alongside the transport as a TransportLocator,
derived from the member's user ID for remote transports and from the
client's domain for our own, and key the connection map on the SFU URL,
the service URL and the server name together so that `url`, service URL
and combined transport shapes are deduplicated consistently.

src/state/CallViewModel/remoteMembers/ConnectionFactory.ts

@@ -43,6 +43,7 @@ export interface ConnectionFactory {
     scope: ObservableScope,
     role: "publisher" | "subscriber",
     transport: UnstableLivekitTransport,
+    serverName: string,
     ownMembershipIdentity: CallMembershipIdentityParts,
     logger: Logger,
   ): Connection;
@@ -95,6 +96,7 @@ export class ECConnectionFactory implements ConnectionFactory {
    *
    * @param scope The observable scope (used for clean-up)
    * @param transport The transport to use for this connection.
+   * @param serverName The name of the homeserver to which the {@link transport} belongs.
    * @param ownMembershipIdentity required to connect (using the jwt service) with the SFU.
    * @param logger The logger instance to use for this connection.
    * @param sfuConfig optional config in case we already have a token for this connection.
@@ -104,6 +106,7 @@ export class ECConnectionFactory implements ConnectionFactory {
     scope: ObservableScope,
     role: "publisher" | "subscriber",
     transport: UnstableLivekitTransport,
+    serverName: string,
     ownMembershipIdentity: CallMembershipIdentityParts,
     logger: Logger,
   ): Connection {
@@ -113,6 +116,7 @@ export class ECConnectionFactory implements ConnectionFactory {
         slotId: this.slotId,
         role,
         transport,
+        serverName,
         client: this.client,
         scope: scope,
         livekitRoomFactory: this.livekitRoomFactory,