Convert Unit Tests to use JUnit 5

[dsrees]

• Moved all tests to use JUnit 5 with nested class structure
• Added Jacoco to generate coverage
• Uploading to codecov

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@a6ee05a). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #60   +/-   ##
=========================================
  Coverage          ?   91.22%           
  Complexity        ?      174           
=========================================
  Files             ?        9           
  Lines             ?      513           
  Branches          ?       66           
=========================================
  Hits              ?      468           
  Misses            ?       13           
  Partials          ?       32

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