[web] Added a prj check to the data-link shortcode.

See merge request ogs/ogs!4223

Images used in Markdown cells need to be in a subdirectory `images` or `figures`! E.g.:

```markdown
![Schematic view of surfing boundary condition benchmark](figures/surfing_schematic.png)
```

Otherwise the images will not appear on the website.

Deduplicated IP data access

See merge request ogs/ogs!4222

Requires prj files to be given as array, e.g:
project = ["project1.prj", "project2.prj"]

and a symlink of Tests into web (super ugly) as hugo cannot access files
outside of its working directory.

Restructuring of the TRM process: Split constitutive setting

See merge request ogs/ogs!4198