Cherrypick Inject EntityManager changes from 8.0-JDK17

[arjantijms]

The commits were initially done on the wrong branch

[OndroMih]

Looks good. When compared with the 8.0-JDK17 branch, the differences are really only about Java version and some minor things that are not compatible with JDK17: https://github.com/eclipse-ee4j/glassfish/compare/8.0-JDK17..arjantijms:glassfish:8.0

There's one missing thing though - the default-web.xml file in the 8.0 branch has 11 for compilerSourceVM and compilerTargetVM JSP compiler params, while in the JDK17 branch it has 17.

@arjantijms , can you also change the JDK versions in the default-web.xml to 21 for the 8.0 branch, in this PR?

[arjantijms]

There's one missing thing though

That's probably a "new" feature that wasn't introduced by the merge or the EntityManager changes, but just something we did in JDK 17 branch and never did in the regular branch. I'll change it though.