Update Singularity pipeline

[manon-but-yes]

This PR updates the Singularity pipeline to allow any user to build and use final and sandbox Singularity containers for this repo.
In particular it:

• fixes the singularity scripts to fulfil the style requirement
• replaces the local base image that was not publicly available with an online base image hosted on Sylabs and containing all the required library
• simplifies the singularity.def
• adds the singularity pipeline to the documentation

[felixchalumeau]

@limbryan @Lookatator @manon-but-yes

Now that the singularity files are "pre-commit friendly", I updated the CI to run all the pre-commits.