Procedure to update the user app

[Mohammer5]

I worked on the user app recently and could see that the app could use some refactoring

• Still uses d2 instead of app-runtime
• Uses material ui instead of @dhis2/ui
• Uses configuration instead of components

I think we should tackle that app (and potentially others with similar issues) as it's becoming increasingly difficult to maintain these apps.
The sms-configuration & scheduler app are quite easy to maintain, so I think we should try to apply a similar approach to the other apps as well.

I guess by upgrading to our UI library and change the architecture from config to components first, we get a lot of complexity out of the way. Then it should be fairly straight forward to add the app-runtime incrementally.

cc @HendrikThePendric @varl @amcgee