Update Jetty and Javalin versions

[ndoschek]

Due to Security alert caused by jetty v9:

• Update Jetty to version >=10 which is available via the current (and newest) Eclipse release
  • Remark: Since 2021-06 Jetty v10 is available, but it caused issues (see also https://github.com/eclipse-emfcloud/emfcloud-modelserver/pull/124). Please investigate what are the problems and how we can overcome them.
  • This means we can remove the (rather instalbe) jetty update site
• Hence update to Eclipse release 2022-12
• Update Javalin to version 5

With 2022-06 Jetty 9 was completeley removed from the Eclipse release and Javalin 5 also switched to Jetty 10, so we should conclude this switch also soon.