test(openchallenges): exclude Java classes generated by OA Generator from coverage report

[tschaffter]

Closes #2331

Description

Exclude .java classes that originate from auto generated code by OpenAPI Generator. The approach taken is to exclude known files that are auto generated. In order to achieve this, I had to move the files *ApiDelegateImpl.java into their own packages.

This approach is implemented for the image service. It will be implemented for other services in future PRs.

Notes

• Force the tests to run instead of using cache with ./gradlew test --rerun-tasks.
• The exclude property expects the name of .class files, not .java files.
• JaCoco synthax:

  * matches zero or more characters
  ** matches zero or more directories
  ? matches a single character
  

Preview

Before excluding any classes:

After excluding classes generated by the OpenAPI Generator: