chore: rename dm-rpc -> json-rpc

...JsonRPCResponder/LlamaCppSubjectActionPromptResponder.php

...tJsonRPCResponder/ObservableTasksTableUpdateResponder.php

src/WebSocketJsonRPCResponderAggregate.php

src/WebSocketJsonRPCResponderInterface.php

src/WebSocketProtocol.php

...WebSocketProtocolController/JsonRPCProtocolController.php

src/WebSocketProtocolException/UnexpectedNotification.php

src/WebSocketProtocolException/UnexpectedRequest.php

src/WebSocketProtocolIteratorTest.php