Provide the ability to set different permissions to access app properties

Currently, the App properties do not provide the ability to set permissions on which users can read or modify those values. The alternative is to leverage User Properties, but those may be too restrictive depending on the use case since only the app or the user associated with it can access the values.

It would be useful to provide a way to define who can access those resources. For example, allowing only administrators to create and modify values, while normal users can only read those properties. Alternatively, a third type of property could be created with that access level, which sits in between App properties and User properties.