Improve update UI

[robin-nitrokey]

• Avoid focus changes between the info frame at the bottom and popup dialogs.
• Include extra information from pynitrokey
• Indicate overall progress (e. g. step x of y)

[daringer]

partly solved by #199

at least the first point, still to-do:

• [ ] show extra info
• [ ] add "step x of y" as description into progress-bar

[isa10110]

Please use the tooling that modern desktop environment offers you for example qt or gtk at Linux

[daringer]

this is already done (nkapp2 uses QT6) - the comment above is about two minor details missing from the update process that are already working on nitropy - not about the gui-toolkit used - please open a new issue if you'd like to improve/discuss the latter.