add headless subpackage

This issue was pinpointed as regression in https://github.com/adoptium/installer/issues/848

Fedora/rehl packages contain headless subkg,m which is jre without graphiclal stack. The package is of nearly same size as would is current headfull package, but the depndencies are gone - about 1gb of dependencis (both manual and generated).
The headfull jre then requires headless jre and it isefl have just desktop integration and awt libraries.. and all the deps.
It is very cool feature, as we know, very widely known. There was request to have headless sdk subpkg, but we nwever made that step.

More detailed info in https://github.com/adoptium/installer/issues/848

@jiekang fyi!

Start by reading the linked regression issue, adoptium/installer#848, then trace the repository's packaging entry points for the existing JRE package. Done means a separate headless JRE subpackage is produced, while the full JRE retains desktop integration and depends on the headless package as described.

Written by the indexing model from the issue text.