Allow a more advanced API feature for managing user's access

At the moment, the user creation api is provided by POST /rest/api/3/user endpoint. This endpoint currently generates inconsistent results and there are no additional create options available.

It would be useful to have additional advance options when managing user's access to sites/organization via API.

• Set if the new user has site access or not (inactive)
• Choose a product access to grant for new user
• Query the product access for each user.
• Change the product access, site/organization access status of an existing user.