GODT-22: Frontend-backend

- GODT-1246 Implement settings view.
- GODT-1257 GODT-1246: Account and Help view
- GODT-1298: Minimal working build (panics)
- GODT-1298: loading QML (needs Popup window)
- GODT-1298: WARN: Adding PopupWindow not possible!
    In therecipe qt the `quickwidgets` classes are within `quick` module, but
    forgot to add library and include paths into cgo flags. Therefore
    compilation fails and it would be hard to patch therecipe in order to
    fix it.

    I am not sure if rewrite PopupWindow into go would make any difference,
    therefore I decided to use normal QML Window without borders.
- GODT-1298: Rework status window, add backend props, slots and signals.
- GODT-1298: Users
- GODT-1298: Login
- GODT-1298: WIP Help and bug report
- GODT-1178: MacOS dock icon control
- GODT-1298: Help, bug report, update and events
- GODT-1298: Apple Mail config and Settings (without cache on disk)

internal/frontend/qml/icons/ic-copy.svg

@@ -0,0 +1,4 @@
+<svg width="12" height="13" viewBox="0 0 12 13" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M4 2V0H12V10H9V9H11V1H5V2H4Z" fill="#262A33"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M0 3V13H8V3H0ZM7 4V12H1V4H7Z" fill="#262A33"/>
+</svg>