Bug#967933: ant-optional: Missing ant-junitlauncher.jar

[Stefan Tauner]

Ok, got it. I missed some additional build requirements for Ant on
Junit5 if one wants to build junitlauncher completely and the whole
confined stuff threw me off.

Interestingly, junit5 is then not needed at runtime anymore - at least
not for how josm uses it. I have not tested other applications though.

I have made some additional useful changes but I do not intend to do a
NMU (yet) - it would be my first and I am not really confident that
this does not break anything - unless instructed to do so.
Feel free to copy any of it:
https://salsa.debian.org/stefanct/ant/-/commits/master

-- 
Kind regards/Mit freundlichen Grüßen, Stefan Tauner