Add support for showing editor feedback to students.

• This feedback is shown after running a test, and will be reset on each new run, or when navigating away from a submission.
• Backend will look for editor-feedback.json, format info included in next message

To get editor feedback in WebLab (Monaco Editor required), the docker container needs to write editor-feedback.json to the output folder.

editor-feedback.json format example:

[
    {
        "file": "SOLUTION", //one of ["LIBRARY", "SOLUTION", "TEST"]
        "startLineNumber": 20, //int
        "endLineNumber": 20, //int
        "severity": "Info", //one of ["Error", "Hint", "Info", "Warning"]
        "message": "100% coverage" //String
         // "startColumn": 1, //optional, int
         // "endColumn": 20 //optional, int
    },
    {
        "file": "LIBRARY",
        "startLineNumber": 41,
        "endLineNumber": 48,
        "severity": "Info",
        "message": "Some message"
    },
  [...]
]

Submitted by Elmer van Chastelet on 17 March 2023 at 10:30