Fixes #9188

[at88mph]

What does this pull request (PR) do? / Que fait cette demande « pull » (PR)?

This PR will add a feature to the wb-postback JSON API that will allow a form to set the desired method to be used when submitting the form via AJAX. This is useful when a PUT request is desired, for example. The setup script was also cleaned up, and, I believe, corrected. The sudo command was being used when the root user was being used, but should be the other way around, I believe.

Additional information (optional) / Information additionnelle (optionel)

General checklist / Liste de contrôle générale
Make your own list for the purpose of your Pull request. /// Faites votre propre liste en fonction des besoins de votre demande « pull ».

• Create/update documentation /// Créer/mettre à jour la documentation
  • Could not find instructions for updating documented API.
• [ X ] Build and test PR's code /// Rouler le script de compilation et tester le code de la PR
• Validate changes against WCAG for accessibility /// Valider les changements avec WCAG pour l'accessibilité
• Ensure documentation is bilingual /// S'assurer que la documentation soit bilingue

Related issues / Requêtes associées
Closes #9188

[duboisp]

See my comments here: #9188 (comment)

In short, I am looking for the rational of using a different method when the form is submitted via Ajax vs when the form is submitted in basic HTML mode, which fallback on the HTML form.