update for feedbackmodel

Description / Overview

The Updatenmethod for the Feedbackmodel is important for being able to give feedback and give the opportunity to correct feedback

Use cases

there are three different usecases:

PATCH /feedback/<id> {
	"score": 12,
	"annotated_lines": {
		...
	}
}

Here is the score changed. But it can't change if there is no change at the Feedback for Submissionlines

PATCH /feedback/<id> {
	// score stays the same
	"annotated_lines": {
		4: {"text": <some modified string>}
	}
}

Here the score stays the same but there is a modified comment or a new one

PATCH /feedback/<id> {
	"annotated_lines": {
		4: {"final": true}
	},
	"final": true
}

here the final-status of this feedback changed

Feature checklist

• the user is able to patch existing feedback
• the first case is implemnted
• the second case is implemented
• the third case is implemented
• tests are written