Add possibility for read only custom user attributes

[victor-butler]

Is your feature request related to a problem? Please describe.
It's a feature request: When adding custom user attributes, add a read only checkbox for the attribute:

If set to read only, only the admin can edit/remove the attribute.

This:

"attributes":
   {
      "distanceUnit": "mi",
      "speedUnit": "kmh"
   }

Would become this:

"attributes":
   {
      "distanceUnit": {
            "edit": 0,         //read only
            "value": "mi"
      },
      "speedUnit": {
            "edit": 1,         //can edit
            "value": "kmh"
      }
   }

Alternative 2 - same as above, we have a checkbox for Read Only but attributes can look like so:

"attributes":
   {
      "distanceUnit": "mi",
      "speedUnit": "kmh".
      "readOnly": {                                 //read only here
            "customAttribute1": "string",
            "customAttribute2": 5
      },
   }

Any thoughts?

[victor-butler]

So finally this is what I came up with:

We don't touch the Attributes field but add a new one called Read Only Attributes, which works in the same was as the Attributes one, except that only an Admin can add and edit those attributes.

This solves the problem for compatibility for already existing APIs and only needs one additional column in the DB:

Same Read Only attributes can be also added for Devices, this will be a useful feature there too.