Migrate all tests to JUnit5

[poikilotherm]

What this PR does / why we need it:
To modernize testing and extend with helpers, etc, we need to move the test base to JUnit 5. Slow migration didn't happen, so let's get this over with.

Which issue(s) this PR closes:

Closes #9782

Special notes for your reviewer:
None. Basically, all tests have not been changed in meaning, but in JUnit API syntax. (As all tests were passing before and are passing now, it's the same state. However, there is a remote chance this change can introduce a testing regression.)

Here are some details on what changes were necessary to complete the task: https://junit.org/junit5/docs/current/user-guide/#migrating-from-junit4

Suggestions on how to test this:
Run all the tests.

Does this PR introduce a user interface change? If mockups are available, please link/include them here:
No

Is there a release notes update needed for this change?:
Probably.

Additional documentation:
Will be included.

[coveralls]

coverage: 19.968% (-0.4%) from 20.37% when pulling 494624b on 9782-migrate-junit5 into 45a3936 on develop.

[poikilotherm]

@pdurbin done - the enforcer takes care of this. If someone accidentally re-introduces JUnit 4, their Maven will fail to execute tests.

[github-actions]

📦 Pushed preview images as

ghcr.io/gdcc/dataverse:9782-migrate-junit5

ghcr.io/gdcc/configbaker:9782-migrate-junit5

🚢 See on GHCR. Use by referencing with full name as printed above, mind the registry name.

[pdurbin]

This failed on Jenkins with this:

TASK [dataverse : build warfile with specified tests using custom maven. tail /tmp/dataverse/mvn.out for gory details.] ***
fatal: [localhost]: FAILED! => {"changed": true, "cmd": "source /etc/profile.d/maven.sh && mvn -DcompilerArgument=-Xlint:unchecked test -P all-unit-tests -Djacoco.skip.instrument=false -T 2C clean package > mvn.out", "delta": "0:02:58.046746", "end": "2023-08-22 06:54:18.219668", "msg": "non-zero return code", "rc": 1, "start": "2023-08-22 06:51:20.172922", "stderr": "", "stderr_lines": [], "stdout": "", "stdout_lines": []}

[pdurbin]

I kicked off another Jenkins run: https://jenkins.dataverse.org/job/IQSS-Dataverse-Develop-PR/job/PR-9796/10/

I also kicked off https://github.com/gdcc/api-test-runner/actions/runs/5940755754 (the new "manual" workflow added by @poikilotherm )

[pdurbin]

I know Jenkins is failing but we have a Slack thread about it: https://iqss.slack.com/archives/C010LA04BCG/p1692718312562289

https://github.com/gdcc/api-test-runner/actions/runs/5940755754 passed so I'm going to approve this PR. Here's where you can see that the correct branch was tested:

[pdurbin]

Looks good!

[pdurbin]

As discussed at standup, I just kicked off a Jenkins run: https://jenkins.dataverse.org/job/IQSS-Dataverse-Develop-PR/job/PR-9796/12/

It should pass now that Jenkins has been updated to Java 17.

[poikilotherm]

Woo-hoo! As always, thanks y'all for taking the time and getting it merged! Much appreciated!