Add API to add/remove connectors of a running jetty server

Patch the ServletContainerAdapter to allow adding/removing listening sockets while the servlet container is running.

This is to allow a custom router implementation to dynamically add or remove network interfaces without having to restart the stream server (this keeps open subscriptions actives)

JettyServletContainer is modified to implement this feature

Modified code is exercised by existing tests.
R i don't want it