Allow per dashboard-element user privileges

### Description

Premise - in production environments, various people interact with HMIs, from engineers, to operators, simple maintainers, SCADA architects, etc.
These HMIs are normally in easy to access locations, specifically for their convenience. However, that creates a problem - anyone that can walk up to the HMI can interact with the HMI/dashboard, including potentially starting/stopping equipment, putting equipment and personnel at risk.
To prevent this, most HMIs by default are in "read only" mode, so someone passing by can view the status of the process, but not manipulate it. If they want to actually interact with the dashboard, they must log in. Depending on the privileges of that user, they can do certain things.
Common user levels are
Admin - full control
Engineer - can fine tune equipment like change operating parameters & alarm setpoints but not completely nuke displays
Operator - can start/stop equipment but not change setpoints that require authorization from engineering
read-only - default user login

If we want NR Dashboard to really challenge traditional HMI/SCADA systems on the production floor, I see this as a feature that will need to eventually be implemented.

For now, having the ability to restrict at a page-level can achieve some degree of user privilege granularity, which is a step in the right direction.

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate