Playground: add minor Side-by-Side tool improvements

[laadvo]

Motivation and Context

After looking over and using the Side-by-Side tool, a few possible improvements were suggested:

1. Making the Title of the following exercise bold in the exercise window (opens whenever the exercise changes)
2. Using mp4s instead of gifs in the tutorial
3. Adding new line to the submission whenever a new feedback is referencing

Description

This PR implements the first two suggested changes. The exercise titles are now bold and in the tutorial videos are used. When trying to implement the third suggestion, it proved to be a lot more challenging than enticipating. Whenever a new line needs to be added to the submissions, it means that the lines being referenced by the other feedbacks need to be updated, resulting in a lot of overhead when wanting the feedbacks to still be displayed bellow the referenced lines. Additionally, it resulted in weird formating, making the submission more difficult to read, since for example sometimes feedbacks by mistake stop referencing it in the middle of a word.

Steps for Testing

1. In Playground select Evaluation Mode and scroll down to Expert Evaluation
2. Select an existing evaluation or create a new one with at least 2 exercises (create, save, start it, add an expert link)
3. Access the expert link and make sure the tutorial steps are videos and no longer gifs
4. Click your way through the evaluation so that you arrive at a new exercise
5. You should see the Exercise window with exercise title in bold

Testserver States

Note

These badges show the state of the test servers.
Green = Currently available, Red = Currently locked
Click on the badges to get to the test servers.

Screenshots

Gifs replaces by Videos in the tutorial:

Bold exercise title: