Allow ReadOnly View of Harbor UI for Specific users.

[ehuizar1028]

Describe the solution you'd like
It would be useful to provide auditors/support the ability to view Harbor's UI from a ReadOnly view. Meaning they can view all configuration and artifacts from a UI view, but the inability to pull actual objects, make changes.

Harbor Robot Accounts has the ability to create granular permissions that looks like we can set ReadOnly style attributes, although Robot Accounts cannot log into the UI. But a solution like this would work also.

[reasonerjt]

I don't think we will allow new preset roles before we allow creating custom roles and assigning such roles to a user.