Update Jetty integration prior to Jetty-10 release

The jetty integration relies on deprecated classes and exposed classpath mechanisms that will no longer be available in jetty-10.

See https://github.com/eclipse/jetty.project/issues/3804 for a discussion as to how Weld integration might be achieved hopefully without hard dependencies nor version sensitivity. Jetty-10 will be in alpha release soon, so it would be good to work out a mechanism that will work and then back port to jetty-9, so that future releases can work on either.