Fixes for `/admin/translations/awaiting`

…and some TypeScript migration

@Avris, please review:

• the changes in Icon.vue (it actually wasn’t necessary to migrate, but I had an issue with mixins which raises errors when using other components, so very, very, weird; but now when it’s there 🤷)
• that the roles in /admin/translations/awaiting / /api/translations/* are like you would do it ;)
• also, I noticed that you removed some time ago the transitions on DialogueBox, was there a particular reason for that?