Consider query strings for context

[pyphilia]

It would be really convenient to be able to set some value via querystrings such as language, view, mode, etc.
This would force the app in a particular context (it would be be prioritised compared to the parent's context).

[spaenleh]

I agree, but with the recent changes, this would have to either go in:

• graasp/ui: where the communication and the context is given to the app (inside the AppItem component)
• builder/player: where the AppItem is instantiated and the contextPayload is created. This was done to remove the need to pass a lot of props to the AppItem component.

But I guess we should extract as much logic from ui as possible.

[codeofmochi]

I don't think this should be in UI either