Get rid of the SystemConfigManager

[abacef]

Is your feature request related to a problem? Please describe.
It is hard to follow the code sometimes because systemConfigManager can be called from anywhere because it is global

Describe the solution you'd like
Remove the SystemConfigManager and maybe refactor the codebase to a version of MVC (because there are many). I am not sure what design pattern this currently follows. It almost follows MVC, but the model package actually specifies domain objects, and the Application package is not really the controller, it is more like a model, except the UIController which is the controller. The UI package is pretty good though.

Describe alternatives you've considered
I attempted to remove the SystemConfigManager and pass each application reference from the members of the SCM into the necessary classes via creating them in MainFrame. This is in the branch no-system-config-manager if you want to take a look at it. Everything functions like it did before except more weird things happen with the UI text sizing, but that was already broken.

Additional context
None