Junit 5 Upgrade

[enzo-inc]

This PR upgrades usages of Junit 4 to Junit 5. In particular:

• The junit-vintage-engine dependency is replaced with the junit-jupiter-engine dependency in all pom.xml files in which it appears.
  • An exception to this is that we retain junit-vintange-engine in dmn-core/pom.xml due to the FEELSuiteIT.java test file. This file uses the FitNesse Runner, and FitNesse does not provide an equivalent mechanism that conforms to Junit 5's Extension model.
• Update json test resources to use "" instead of "\"\"" for empty annotations. The tests using these resources were not being run before, but with the introduction of the jupiter-engine, they are now running and failing due to the use of "\"\"". The assumption is that "" is the correct format for specifying an empty annotation, ensuring consistency across test resources and fixing the test failures.
• Update the template ftl files and corresponding test files under dmn-test-cases to use @org.junit.jupiter.api.Test annotations instead of @org.junit.Test
• We update any Junit 4 import statements and expressions in the remaining java test files.

[opatrascoiu]

Thank you for your contribution :)

[enzo-inc]

Regarding the usage of the FitNesse Runner in FEELSuiteIT.java, how would you think about migrating this functionality to a Junit 5 compliant format?