Remove unmaintained modules

A few modules are versioned since the initial PoC but, as not documented, are not used in the rest of the codebase and are likely to be replaced by alternatives.
In addition, some packages are pulling dependencies that are polluting our PRs with useless upgrades.
Some other packages are introducing large artifacts that are making the front-end code larger than needed.
The code will be removed but can be easily retrieved using Git history.
The list of removed packages is the following:

• @xwiki/cristal-rendering
• @xwiki/cristal-macros
• @xwiki/cristal-rendering-wikimodel

Note: Associated (also unused) APIs will be removed.