Make status and importance sortable again

[vkbo]

Summary:

With the rewritten NWStatus class, the status and importance flags can be sortable again. This PR implements this feature again. Although, not with drag and drop as before, but with buttons.

Related Issue(s):

Resolves #1035

Reviewer's Checklist:

• The header of all files contain a reference to the repository license
• The overall test coverage is increased or remains the same as before
• All tests are passing
• All flake8 checks are passing and the style guide is followed
• Documentation (as docstrings) is complete and understandable
• Only files that have been actively changed are committed