Add test case for multivalue x-forwarded host header

Issue: SPR-11140
Consistent ".jetty" and ".standard" subpackages; consolidated GlassFishRequestUpgradeStrategy implementation; renamed Text/BinaryWebSocketHandler and moved them to web.socket.support
Use port scanning for JMX tests

Attempt to fix performance build by scanning for a free JMX port.
Add principal in GlassfishRequestUpgradeStrategy
Document websocket XML namespace

Issue: SPR-11063