Self-made deb and rpm packages

[koppor]

This tracks the state of jabref-issued deb and rpm packages.

We are experimenting using https://github.com/nebula-plugins/gradle-ospackage-plugin on the branch https://github.com/JabRef/jabref/tree/deb-and-rpm.

Current state: jar is packed into the deb. No startup scripts, no desktop integration.

This issue becomes obsolete in case JabRef is fully integrated with all features in Debian - see JabRef#135.

[koppor]

@fnatter managed to create one deb package for Freeplane:

https://github.com/freeplane/freeplane/blob/1.6.x/linux-packages.gradle

[Siedlerchr]

This is now implemented by #5312
Deb and rpm packages are now generated using the jlink and jpackage combination.

[koppor]

I got the tooling hint (at https://twitter.com/sanjay_ankur/status/1309211294743093249) to publish an rpm: https://copr.fedorainfracloud.org/. Seems to be difficult: https://twitter.com/koppor/status/1312405808873975808