Jetty upgrade

[holgerfriedrich]

For the upcoming OH6/Karaf 4.5 release, we will use Jetty 12 and would appreciate a release that is build against this version.
Jetty 9 to Jetty 12 also comes with the javax to jakarta migration.

As of now, Karaf 4.5. SNAPSHOT uses Jetty 12.0.23.