Implement invitation modal / invitation flow

[dromerolovo]

Small Description:

The current CMS only allows for admin invitation, but it needs to be replaced with a system that allows admins to invite moderators and promote them to admin. After the update, admins will have two options available: inviting moderators and promoting them to admin.

• Create the UI of the modal, this issue depends on the issue Design new invitation modal #54
• Implement the necessary changes to support this regarding the infrastructure / repository. AuthApiRepository
  This depends on a change that is needed on the api. But the base of the repository could be changed anyway. Right now there's no endpoint to perform the "moderator invitation process". But we could use something like v1/auth/invite-moderator. And leave it there till the endpoint is ready.
• Implement the necessary changes to support this regarding the application / bloc. AuthBloc
• Implement the necessary changes to support this regarding UI / infrastructure(repos) / application(bloc). E.g changing naming of "invite admin" to "invite moderator" in cases that are appropriate.

[Xazin]

We don't need this, we only actually want to invite Moderators.

So what we need to do, is to make a small change on the backend and it will be fine.

We need another way, for Admins to manage Admins and Moderators, so that a moderator can be promoted by an Admin.

[dromerolovo]

Ok, so an admin would be able to make two actions: 1. Invite a moderator, 2. Promote a moderator to admin, right?

[Xazin]

Ok, so an admin would be able to make two actions: 1. Invite a moderator, 2. Promote a moderator to admin, right?

Yes