Require authentication to participate in chat (#4762)

* feat(chat): require authentication to participate in chat

* fix: it's pretty much impossible to bypass the auth requirement, addressing review feedback anyway

* feat(chat): render chat text input as disabled if chat auth is required

* Commit updated API documentation

---------

Co-authored-by: Owncast <owncast@owncast.online>

core/chat/server.go

@@ -397,6 +397,14 @@ func (s *Server) eventReceived(event chatClientEvent) {
 		return
 	}
 
+	// Check if authentication is required for chat
+	if configRepository.GetChatRequireAuthentication() {
+		if u == nil || (!u.Authenticated && !u.IsModerator()) {
+			s.sendActionToClient(c, "Authentication is required to participate in chat.")
+			return
+		}
+	}
+
 	var typecheck map[string]interface{}
 	if err := json.Unmarshal(event.data, &typecheck); err != nil {
 		log.Debugln(err)