Declarative Jenkins pipeline

[bilke]

This is a PR migrating Jenkins scripts to the Declarative Pipeline which has some benefits:

• Easier to read, with some sane defaults for typical things such as setting environments, doing something as a post-step, ..., just have a look at the changed Jenkinsfile which at the moment contains basically the same logic as gcc-conan.groovy and msvc.groovy
• Better visualization in the blue ocean Jenkins UI. You can click on the graph to see all steps which belong to a parallel sub-job. Also there are nice pages for tests and artifacts. I think this is a huge advantage, no more drilling down which step failed in the overwhelming pipeline steps view
• Actively developed; it is advised to use the declarative pipeline for the general structure and if necessary more low-level code in the pipeline library

I would like to hear your thoughts. If you agree to the migration I will finish this PR by migrating the remaining sub-jobs.

Caveats

• Steps can't be hidden from the pipeline view, e.g. there are lots of steps labelled Checks if running on a Unix-like node which have no meaning for the user and clutter the view. Maybe this can be addressed in a future version of the declarative pipeline / blue ocean UI

[endJunction]

Looks good. One can still go to the "usual" pipeline steps and see the (overwhelming) details.

[chleh]

Minor: It would be better to disabled unit tests like this: ✅

#ifndef USE_PETSC
TYPED_TEST(NumLibODEIntTyped, T1)
#else
TYPED_TEST(NumLibODEIntTyped, DISABLED_T1)
#endif

This way the test will be compiled at least and ctest will tell you about it being disabled.

[bilke]

Is now ready to merge.

[ogsbot]

OpenGeoSys development has been moved to GitLab.

See this pull request on GitLab.