Bitcoin Core App: QT GUI Inspection

Some of the people working in a the Bitcoin Core App got together to review and discuss the UI of the current GUI. Goal was to understand the UI, supported features, interaction models, etc. This should help inform design decisions for the new app.

For more context, see:
https://github.com/bitcoin-core/gui-qml
https://bitcoindesign.github.io/Bitcoin-Core-App/