Chatting as guest calls "GuestManager::updateName" for every message

[fancycode]

Steps to reproduce

1. Connect as guest user to a room.
2. Send chat messages.

Expected behaviour

The name of the user should not be updated if it didn't change.

Actual behaviour

GuestController::updateName is called for every message:

spreed/lib/Controller/ChatController.php

Line 191 in 4c9d7e7

$this->guestManager->updateName($room, $sessionId, $actorDisplayName);

This should either only be done if the name has changed, or updateName should detect the same name internally and perform a no-op in such cases.

Updating the name causes unnecessary database updates and unnecessarily reloads of the participant list by all clients.