CRUD sub users for project

[eddiejaoude]

Within a project we need to add the CRUD users functionality for admins (see screenshot below).

Steps

1. Click new users button in a project
2. In the new users section, there will be list page with delete, create page

Validation

• username can not be added twice

Create

For the user form it needs a string (username), this will be a GitHub username, we need to find that user on our platform and save their uid under project.access.admin or project.access.readonly depending on the dropdown of 2 options admin / readonly AccessModel

Notes: Keep the styling vanilla as possible, this will come later