Introduce DrawingContext Push/PopRenderOptions

[Gillibald]

What does the pull request do?

public override void Render(DrawingContext context)
{
    using (context.PushRenderOptions(new RenderOptions { EdgeMode = EdgeMode.Aliased }))
    {
        context.DrawEllipse(....);
    }

    using (context.PushRenderOptions(new RenderOptions { EdgeMode = EdgeMode.Antialias }))
    {
        context.DrawEllipse(....)
    }
}

What is the current behavior?

What is the updated/expected behavior with this PR?

How was the solution implemented (if it's not obvious)?

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/Documentation with user documentation

Breaking changes

Obsoletions / Deprecations

Fixed issues

[avaloniaui-team]

You can test this PR using the following package version. 11.0.999-cibuild0038985-beta. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[avaloniaui-team]

You can test this PR using the following package version. 11.0.999-cibuild0038988-beta. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]