fix-27_super-old_deprecated_packaging_practices

Fixes https://git.domainepublic.net/Neutrinet/neutrinet_ynh/-/issues/27

I checked with the package_check tool and cleaned everything up. This included generating the README files with https://github.com/YunoHost/apps/tree/master/tools/README-generator. I had to do some manual modifications, but tried to have the result as close to a generated README.md as possible.

• Warnings we still have:
  • ! The application has no associated category in YunoHost's apps catalog
    • Will be fixed with https://github.com/YunoHost/apps/pull/1306
  • ! Consider adding your app to the YunoHost-Apps organization to allow the community to contribute more easily
    • Doesn't make sense for our case, so we'll keep it as is. I made an issue to have it as an Info instead: https://github.com/YunoHost/package_check/issues/116
• The linter also gives info
  • - 'url' is not meant to be the URL of the YunoHost package, but rather the website or repo of the upstream app itself...
    • It's just an info, and in this case we can say that the package kinda is it's own thing, so it makes sense in this case that the url is the package.
• The README_fr.md has some English parts because it took it from the files doc/DESCRIPTION.md and doc/DISCLAIMER.md
  • I assume you can add doc/DESCRIPTION_fr.md and doc/DISCLAIMER_fr.md. Feel free to and I'll generate and adapt them again.

The package_check tool currently does 8 tests. More and custom tests are also possible, but are out of scope for this MR imo. Installation test also test removal and reinstallation after removal. It also tests if the resource is accessible by doing a call and expecting a status 200. We do not currently test the certificate check and renewal part. Step 7 is upgrade from the current stable version.

1. Package linter
2. Installation on the root
3. Installation in a sub path
4. Installation in private mode
5. Backup/Restore
6. Upgrade from the same version
7. Upgrade from 7afd659c
8. Change URL

Summary

 ============================================
 Tests summary
 ============================================


Package linter:                OK  (2 warnings, 1 possible improvements)
Install (root):                OK
Install (subdir):              OK
Install (private):             OK
Backup/restore:                OK
Upgrade:                       OK
Upgrade (7afd659c):            OK
Change url:                    OK

Level results
=============
Level 1 (Installable in at least one scenario)    OK
Level 2 (Installable in all scenarios)            OK
Level 3 (Can be upgraded)                         OK
Level 4 (Can be backup/restored)                  OK
Level 5 (No linter errors)                        OK
Level 6 (App is in a community-operated git org)  OK
Level 7 (Pass all tests + no linter warnings)    
Level 8 (Maintained and long-term good quality)  
Level 9 (Flagged high-quality in app catalog)    

Global level for this application: 6 (App is in a community-operated git org)

(Protip™ for CI admin: you should 'apt install wkhtmltopdf optipng --no-install-recommends' to enable result summary export to .png)
Global working time for all tests: 30 minutes, 35 seconds (01:01:34)