Expose WindowId-based WinRT API to create CanvasSwapChain-s for HWNDs about win2d HOT 1 OPEN

Notes from API review

• Proposed APIs look good, but let's first only add the last two overloads with explicit parameters for size and DPIs. This will make it clearer for consumers they have to manage DPI changes and size manually. We can add more later if necessary.

public sealed class CanvasSwapChain
{
    public static CanvasSwapChain CreateForWindowId(
        WindowId windowId,
        uint width,
        uint height,
        float dpi);

    public static CanvasSwapChain CreateForWindowId(
        WindowId windowId,
        uint width,
        uint height,
        float dpi,
        DirectXPixelFormat format,
        int bufferCount);
}

• We will be adding these to both WASDK and UWP to continue keeping the two branches in sync. The namespace of WindowId is different across the two targets, but this is already a common pattern with other APIs from WASDK as well.
• We will investigate more how best to handle runtime checks or SDK checks in general, as the necessary interop APIs for WindowId are only available on recent Windows 11 SDKs for UWP. So for now, we'll start by only adding these two APIs to the WASDK branch, and add them to the UWP one too after we figure out a strategy for this we are comfortable with.

from win2d.