Simplify test directory structure & github actions

[recalcitrantsupplant]

The SPARQL client should only need one SPARQL endpoint now that SPARQL endpoints have been merged.

This should allow for a single confest.py and the collapsing / removal of all of the subdirectories / complexity in github actions such as:

      - name: Run tests
        run: |
          cd tests/spaceprez && poetry run pytest
          cd ../vocprez && poetry run pytest
          cd ../catprez && poetry run pytest
          cd ../profiles && poetry run pytest
          cd ../services && poetry run pytest