Wifi support and much more

[KenVanHoeylandt]

This was initially planned as "just a wifi app", but the creaks in the app architecture surfaced rather quickly. That's why a lot of things got refactored in this PR while creating the Wifi service and app.

I wanted to break up a complex wifi app with multiple screens into multiple smaller apps. To accomplish this, I needed an app stack on which I could push and pop app instances. The model is inspired by Android app lifecycle, but it's much more simplified than Android.

Other changes were either bugs found along the way (e.g. colour fixes for displays) or quality-of-life improvements for development, like auto-app-start.

Changes

• Refactor App into App+AppData
• Refactor Service into Service+ServiceData
• Introduced Bundle concept for app args.
• Refactored Loader to have a stack of apps that it can start/show/hide/stop.
• Refactored Gui to be more simplified: no more layers for now. It only renders the active app (or desktop)
• Refactored widgets and created ui/ folder.
• Created Wifi service and client app
• Fixed issue with display drivers (RGB <> BGR) so colours are now correct
• Expose graphics&touch drivers individually for both devices
• Refactored desktop from service to app
• Config support for auto-starting of apps
• sdkconfig improvements
• FPS boost to roughly 60 fps (17ms delay is fine, but 16ms hangs touch due to an LVGL bug)