[Spike] Figure out the scope of required UI improvements

Together with brook_cronin_qt.

The current UI is getting overloaded with amount of new export options, is very "in your face" with complex bridge and qml specific custom properties, unreactive and generally not helpful for anything but clicking "export".

Besides that, due to the new Plugin APIs, export time might increase drastically, so we should be able to provide better display of the ongoing export process.

We should figure out and formalize all of the pain points, propose solutions and design a UI that is capable of carrying the improved functionality.