Cover url transports end to end

The specs replace the transports the e2e homeserver advertises with each
shape a migrating deployment may produce and record which token endpoints
each side used: a url-only or combined transport on both sides goes
through the CS API alone, a legacy guest joining a url host uses the
legacy endpoint to publish and the CS API to subscribe, a subscriber falls
back to the JWT service when the homeserver lacks MSC4195, a publisher
gets an error instead, a delayed leave delegated through the CS API fires
on disconnect, and subscribers get tokens for a remote homeserver's SFU
over federation.

The JWT service's app service registration has to cover users of the e2e
Synapse's real server name for the get_token flow, and lk-jwt-service
0.8.0 implements the endpoints.

backend/app-service-othersite.yaml

@@ -5,7 +5,7 @@ sender_localpart: "_lk_jwt_service"
 namespaces:
   users:
     - exclusive: false
-      regex: "@.*:homeserver-1" # Cover all local users
+      regex: "@.*:synapse\\.othersite\\.m\\.localhost" # Cover all local users
 # Required for Synapse to call POST /_matrix/app/v1/ping on this service.
 url: "http://auth-server-1:16080"
 # Enable membership look-ups via /is_joined.

backend/app-service.yaml

@@ -5,7 +5,7 @@ sender_localpart: "_lk_jwt_service"
 namespaces:
   users:
     - exclusive: false
-      regex: "@.*:homeserver" # Cover all local users
+      regex: "@.*:synapse\\.m\\.localhost" # Cover all local users
 # Required for Synapse to call POST /_matrix/app/v1/ping on this service.
 url: "http://auth-server:6080"
 # Enable membership look-ups via /is_joined.