This PR adds MinSize and MaxSize to AnchorLayoutData, making it easier to define size constraints directly within the layout data.

Why?
I was discussing this with a friend, and we both found the current way a bit unintuitive to set the minSize in the widget options. When trying to set min/max sizes, we instinctively looked for those properties in AnchorLayoutData, not in WidgetOpts. Having to set MinSize separately on the widget felt disconnected from the layout itself.

With this change, you can now define MinSize and MaxSize directly in AnchorLayoutData, making it more natural to work with:

Before (current way, still works):

innerContainer := widget.NewContainer(
	widget.ContainerOpts.BackgroundImage(image.NewNineSliceColor(color.NRGBA{255, 0, 0, 255})),
	widget.ContainerOpts.WidgetOpts(
		widget.WidgetOpts.LayoutData(widget.AnchorLayoutData{
			HorizontalPosition: widget.AnchorLayoutPositionCenter,
			VerticalPosition:   widget.AnchorLayoutPositionCenter,
			StretchHorizontal:  true,
			StretchVertical:    false,
		}),
		widget.WidgetOpts.MinSize(100, 100), 
	),
)

After (my change, I think is look more intuitive):

innerContainer := widget.NewContainer(
	widget.ContainerOpts.BackgroundImage(image.NewNineSliceColor(color.NRGBA{255, 0, 0, 255})),
	widget.ContainerOpts.WidgetOpts(
		widget.WidgetOpts.LayoutData(widget.AnchorLayoutData{
			HorizontalPosition: widget.AnchorLayoutPositionCenter,
			VerticalPosition:   widget.AnchorLayoutPositionCenter,
			StretchHorizontal:  true,
			StretchVertical:    false,
			MinSize:            widget.AnchorLayoutDataOpts.AnchorLayoutMinSize(100, 100),
			MaxSize:            widget.AnchorLayoutDataOpts.AnchorLayoutMaxSize(300, 300),
		}),
	),
)

With min size:

With min and max size:

Important:

The old way still works—this just adds an alternative way to set size constraints directly in the layout.

MaxSize didn’t exist before, so this also introduces a way to cap widget sizes inside AnchorLayout.

This should make it easier to reason about layout constraints while keeping everything backward-compatible.