Feature/http response code

[ColonelMoutarde]

Changes proposed in this pull request:

• http code is now replace by constant

Pull request checklist:

• clear commit messages
• code manually tested

[Alkarex]

Plenty of dead code there. In think a short subset could potentially be done after we update the requirements to PHP 8.1+ with enum https://php.net/language.types.enumerations

[ColonelMoutarde]

Plenty of dead code there. In think a short subset could potentially be done after we update the requirements to PHP 8.1+ with enum https://php.net/language.types.enumerations

If we follow the roadmap, it won't be for another 2 years... that's a long time, and a small refacto at that point will be easy.