Add JUnit 5 support

[ErwinOlie]

• Updated bin/run.sh and examples/template/pom.xml to support JUnit 5.
• Renamed existing tests under /tests/ to add -junit4 suffix.
• For each of the JUnit 4 test under /tests/ a JUnit 5 variation is added.

[github-actions]

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[ErwinOlie]

@ErikSchierboom ready for review

[ErikSchierboom]

Great work! I love that you kept the existing test cases too as regression tests.

[ErikSchierboom]

@ErwinOlie is the next step to update the exercises in the kotlin repo to use JUnit 5?

[ErwinOlie]

@ErikSchierboom I don't think it's necessary for the performance improvement ideas. We can backwards support jUnit4 with junit5-vintage-api. However I haven't tried this yet