Install the examples to the correct place for key4hep-stack installations

[tmadlener]

BEGINRELEASENOTES

• Examples and other shared resources should go to <prefix>/share/k4MarlinWrapper in order for key4hep-stack environment variables to be properly populated. This fixes a problem where $K4MARLINWRAPPER points to an empty directory.
• Make sure to run the doctest workflows using the newly built version of k4MarlinWrapper
• Add CEDViaWrapper to the things that are run in the doctest workflow.
• Update github actions versions in CI.

ENDRELEASENOTES

• The CEDViewer via wrapper example is not currently run in the doctest workflow, otherwise we should have realized this much earlier. I am not yet entirely sure if we can run that in a non-interactive shell though.
  • Check if the example can be run

[ebrondol]

Thanks Thomas for the prompt fix.