Add support for detecting if a grading config will work with an exercise that doesn't need exceptions

[Luro02]

The use case is to choose an exercise from a list that can be used with the specified grading config.

The current solution is to parse the grading config with the provided exercise and if it throws an exception, assume it's incompatible with the given exercise.

Obviously this is suboptimal, because

• it can not differentiate between an invalid config and one where the version is incompatible
• every time the string has to be parsed again, resulting in unnecessary overhead
• the code doesn't look nice

A potential solution would be to introduce an intermediate class that can later be converted to the GradingConfig type?

Maybe something like this:

public class ParsedGradingConfig {
  private final GradingConfigDTO dto;

  public boolean isSupported(Exercise exercise) {
    // ...
  }

  public GradingConfig toConfig(Exercise exercise) throws ArtemisException {
    // ...
  }
}