add participant_limit_reached error code

Author: su225

protobuf/video/sfu/models/models.pb.go

@@ -217,6 +217,7 @@ enum ErrorCode {
   ERROR_CODE_PARTICIPANT_SIGNAL_LOST = 206;
 
   ERROR_CODE_CALL_NOT_FOUND = 300;
+  ERROR_CODE_CALL_PARTICIPANT_LIMIT_REACHED = 301;
 
   ERROR_CODE_REQUEST_VALIDATION_FAILED = 400;
   ERROR_CODE_UNAUTHENTICATED = 401;