Grading batch rework

[alexstaeding]

Adds some missing abstraction in the batch loading process.

Breaking changes

This PR makes several breaking changes in the grader and solution loading mechanisms. Solution jars are no longer separate from the grader jar.

Instead, the grader contains all (source) files from the grader and the solution together. To differentiate between grader and solution classes, there is a new grader-info.json (analogous to submission-info.json for submissions) that contains information as to which files are part of the grader, and which are part of the solution.

The format is as follows:

{
  "name": "example-grader",
  "assignmentIds": ["h03"],
  "sourceSets": [
    {
      "name": "grader",
      "files": [
        "h03\\H03_RubricProvider.java",
        "h03\\TutorTests.java"
      ]
    },
    {
      "name": "solution",
      "files": [
        "h03\\Main.java"
      ]
    }
  ]
}

New API

The following methods were added to RubricConfiguration:

  List<String> getFileNameSolutionOverrides();

  RubricConfiguration addFileNameSolutionOverride(String fileName);

  default RubricConfiguration addFileNameSolutionOverride(Class<?> clazz) {
    return addFileNameSolutionOverride(Type.getInternalName(clazz) + ".java");
  }

It is now possible to specify files that should be completely replaced in the submission from the solution.