Allow opening new window for XAML files

Is your feature request related to a problem? Please describe.

I large files it can be useful or even necessary to be able to see and edit different sections together that are far apart in the file. The Window menu in Visual Studio has the "New Window" and "Split" items to facilitate that, but neither of those work for .axaml files with this extension, making it impossible to view more than one location in a XAML file at a time.

Describe the solution you'd like

The "New Window" and "Split" items work the same way with .axaml files as they do with any other file, opening and additional document tab for the currently active file, or adding a moveable splitter in the middle of the window, respectively.

Describe alternatives you've considered

As a crutch, it would be possible to open the respective XAML file in another application that should at least provide XAML syntax highlighting, and view it side by side with Visual Studio, but that additional view would then have very limited functionality.

Additional context

No response

AvaloniaUI / AvaloniaVS