Upgrade to Jetty 12

[niloc132]

See also #4703.

Jetty 11 (and 10) has reached End of Community Support, with End of Life tentatively scheduled for Jan 2025.

Beyond incrementing version numbers, updating to Jetty 12 will require some changes to our dependencies, and a few minor changes to JettyBackedGrpcServer.

Moving to Jetty 12 will require Java 17 as the minimum runtime version for the server.

One option could be to add a server-jetty12 and server-jetty12-app, and deprecate the server-jetty/server-jetty-app modules, but leave them in place for some time (as we have done with the netty modules).

[devinrsmith]

I would probably argue that jetty-12 should keep the existing package name, and a jetty-11 would get server-jetty11, etc.