Images from exercise descriptions are not exported under certain conditions

[chrisknedl]

Describe the bug

In an exercise description, images can be included in the markdown text, for example
![some_image](/api/files/markdown/Markdown_2023-05-08T09-19-43-656_7ec9f47f.png).
When downloading this exercise, the image file is included in the files/ subdirectory of the exercise folder.

The issue arises when an additional tooltip-text is provided in the markdown, like this:
![some_image](/api/files/markdown/Markdown_2023-05-08T09-19-43-656_7ec9f47f.png "ShownOnHover").
In this case, the image is not part of the exercise export.

This is most likely an issue with the related regular expression.

To Reproduce

1. Create an exercise
2. Add an image to the exercise description (e.g. by dragging and dropping an image into the text area)
3. Add a tooltip text as described above, e.g. "ShownOnHover"
4. Save the exercise, and download it using the 'Download Exercise' button in the exercise's overview page
5. Unzip it, and look inside the files/ directory. It shouldn't contain the image

Expected behavior

The image should be included in the downloaded directory.

Screenshots

n/a

Which version of Artemis are you seeing the problem on?

7.2.2

What browsers are you seeing the problem on?

Chrome, Safari

Additional context

No response

Relevant log output

No response