enhance JuliaPackage easyblock to avoid writing to $HOME & clean up JuliaBundle

[Flamefire]

(created using eb --new-pr)

Some easyconfigs have sanity check commands that run e.g. julia -e ...

This will use the $JULIA_DEPOT_PATH set in the module which is something like :/foo:/bar where the leading colon means "including the user depot": https://docs.julialang.org/en/v1/manual/environment-variables/#JULIA_DEPOT_PATH

That will write artifacts/cache files to $HOME/.julia or fail if that's not writable.

Similar to PythonPackage/PythonBundle use a temporary directory for that and end with a trailing colon for "excluding the user depot."

Additionally some empty methods on Juliabundle can be removed

[Flamefire]

Test report by @Flamefire

Overview of tested easyconfigs (in order)

• SUCCESS Circuitscape-5.12.3-Julia-1.9.2.eb

• FAIL RCall-0.13.17-foss-2022a-R-4.2.1-Julia-1.9.2.eb (build issue)
  (partial log available at https://gist.github.com/Flamefire/03cea4930daf40ee7031beee49666fa1)

• SUCCESS Circuitscape-5.12.3-Julia-1.7.2.eb

Build succeeded for 2 out of 3 (total: 1 hour 12 mins 55 secs) (3 easyconfigs in total)
i7140 - Linux Rocky Linux 9.6, x86_64, AMD EPYC 7702 64-Core Processor (zen2), Python 3.9.21
See https://gist.github.com/Flamefire/d5fcfa06e0bfd1bbdfa15bf0e3ef2c6c for a full test report.

[Flamefire]

The only failure above is from a test failing due to German locale: "Warnung != Warning"
Fix in easybuilders/easybuild-easyconfigs#25666

[boegel]

@lexming Can you take a look at this?