Support DialogHost Ownership for UserControl or any Control (Browser/MainView scenarios)

[0verflux]

Currently, DialogHost appears to be tightly coupled to MainWindow, which limits its usability in non-windowed contexts.

In scenarios such as browser-based targets or modular-layouts where the root view is a UserControl (or another Control that represents MainView), there's no MainWindow available to own or host the dialog, which makes it unusable.

Any plans for DialogHost to support being owned or attached to a control, or any visual root, rather than requiring a MainWindow?