Updating to jetty-project:21-SNAPSHOT
Updating clirr comparison to first released 9.1
formatting cleanup
Removing conflicting javax.websocket:javax.websocket-client-api artifact
423804 - WebSocket / JSR improper use of ServerEndpointConfig.Configurator.getNegotiatedSubprotocol()

+ Correcting BasicServerEndpointConfigurator response for no subprotocol
+ Correcting JsrCreator assumption for no subprotocol
Cleanup (Imports / StandardCharset / Dead APIs)