Document roles and permissions

[mmattel]

Fixes: #207 (Document user roles concept/feature)

[mmattel]

@tbsbdr @kulmann @micbar
Finally, the PR is in a reviewable state. Could you please have a look on if things are correct.

@phil-davis though @EParzefall has already reviewed, mind to have a look on?

You can see a testbuild on staging which includes the review of @EParzefall

I am thinking about to add a note to the security aspects document with regards to roles and permissions, but will do that in another PR.

[mmattel]

Converting to draft because one part is now in the webui documentation and the other part needs to be updated. Waiting for dev input on describing the permission types.

[mmattel]

owncloud/ocis#5318 (graph: add appRoleAssignments and minimal application resource)

[mmattel]

owncloud/ocis#5441 (Space Management Permissions)

[phil-davis]

Note: the "Guest" role was renamed to "User Light".
owncloud/ocis@fc80729
So any documentation of roles needs to have "User Light" (or maybe the technical string that is the role name is "UserLight"?)

[micbar]

@phil-davis Yes. "guest" was totally misleading.

1. Roles are always about permissions
2. User types (Member, Guest) are properties of the user

We need to make sure that these two things are not bound to each other.

[phil-davis]

@micbar I want to clarify the terminology.
Where I said "the "Guest" role was renamed to "User Light"."
I should say "the "Guest" user type was renamed to "User Light"."

Is that correct?

[micbar]

@phil-davis no, you were correct. The role was renamed to avoid confusion.

Basically a user of type guest can have any role in ocis, even the "Admin" role.