Migrate to JUnit 5, apply JUnit best practices

[JPercival]

• Migrate all tests to Junit 5
• Apply Junit 5 best practices where possible (such as omitting the public modifier)
• Fix various errors, like parameter ordering

[github-actions]

Formatting check succeeded!

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 62.27%. Comparing base (c4ceada) to head (2995994).

Files	Patch %	Lines
...n/java/org/cqframework/fhir/utilities/IGUtils.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1360   +/-   ##
=========================================
  Coverage     62.26%   62.27%           
+ Complexity     6954     6952    -2     
=========================================
  Files           492      492           
  Lines         27732    27727    -5     
  Branches       5506     5506           
=========================================
- Hits          17268    17266    -2     
+ Misses         8201     8197    -4     
- Partials       2263     2264    +1     

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