Fix space available widget - ref #6719

[Coussecousse]

Hi !

I refactored the code and implemented the space chart based on Chamilo v1.
I also added the ability to view other teachers’ spaces (it just felt right somehow).
I’m not sure if it works with groups, since I couldn’t find where to test that — hopefully someone can check! Theoretically, it should 😆

I hope my code is fine !

Issue : #6719

Screens :

If error :

(It is centered, I fixed it in the commit Minor — I just took the screenshot before noticing it wasn’t.)

⚠️ To test sessions, I had to create one and try it through another teacher. I noticed it didn’t work at first, so I fixed it — I’ll create another PR for that.