gh-36151: Coxeter arrangement
adding the Coxeter arrangement to the catalog
### :memo: Checklist
- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [x] I have created tests covering the changes.
- [x] I have updated the documentation accordingly.
URL: https://github.com/sagemath/sage/pull/36151
Reported by: Frédéric Chapoton
Reviewer(s): Travis Scrimshaw
