Changing the resolution of headless rendering

[Rosentti]

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

Cannot change the resolution that Avalonia renders headlessly at. I want a 1920x1080 image, but the headless backend only gives 1024x768.

Describe the solution you'd like

A way to set the resolution of headless rendering and change it at runtime whenever.
I guess ClientSize could be made writable or an extension method could be written.

Describe alternatives you've considered

Scaling up the low-res image.

Additional context

Setting the Width and Height does not seem to change the ClientSize.