replace the "piority" labels with a projects custom field

[nweldev]

• [x] add the custom field to all existing projects
• [ ] make sure all issues can be associated with a project
• [ ] (maybe) remove the labels from the config

[nweldev]

New custom field "priorities" created in the blindnet devkit project with the following values:

• ☄ (0) Critical
• 🌋 (1) Crucial
  • fix #10
• 🏔 (2) Required
• 🏠 (3) Necessary
• 🏕 (4) Useful
• 🏝 (5) Nice to have

Then, we'll need:

1. to replace the associated labels with this field in all already prioritized issues in the blindnet devkit project
   • I can't easily automate moving from labels to project custom field, as the CLI doesn't support projects. So we'll have to do this progressively.
     1. to update the existing views to order by priority
     2. to replicate this custom field in all other projects
   • I'll need to check if there is a way to configure that for the whole organization, but I don't think there is (and again, I could update the .github project with a script calling the GitHub API for that, but I don't think it is relevant right now).
     1. to replace the associated labels with this field in all already prioritized in all other project
     2. remove associated labels from .github configuration

[nweldev]

Done in all projects, including for iterations, except for client (sales & SE) and Community, as prioritization isn't handled the same way in these projects.