Evaluate new UI libraries

[dragetd]

We have been using libui with it's c-binding/cgo which works, but has been less than optional. Mostly the cross-building for platforms remains a huge PITA. There have been developments in the last years, which we could take a look at.

• https://github.com/fyne-io/fyne (native go)
• https://gioui.org/ (native go)

Or if we stick to cgo, the qt binding seems still a lot more powerful:

• https://github.com/therecipe/qt

Or custom Windows support, as this is one of our main targets:

• https://github.com/lxn/walk