Migrate tests to JUnit5

[strangelookingnerd]

This PR aims to migrate all tests to JUnit5.

Migration includes:

• Using JUnit5 annotations
• Using Assertions over Assert
• Remove public modifiers from test classes and methods
• Clean up assertions (switching expected and actual, simplyifing assertions...)
• Trivial code cleanup

I validated my changes using mvn verify and noticed that one test failed before and after my changes, others pass just fine.

[ERROR] Failures: 
[ERROR]   DatasetJenaTest>AbstractDatasetTest.testStreamDefaultGraphNameByPattern:704 expected: <null> but was: <<http://example.com/graph1>>

[garydgregory]

Hello @strangelookingnerd

Thank you for your PR.

It looks like every line in pom.xml has been edited, and so creates a conflict.

Would you mind resolving this?

[garydgregory]

Hi @strangelookingnerd
Same comments as for apache/commons-dbutils#324, especially non-required noisy changes that make the PR bigger and harder to review.
TY!