Core: better approximation for Label desired size

When getting desired size with constraints (0, infinity),
instead of trying to fit the text by splitting it into as many
lines as possible (which can lead to too much requested
height), try to approximate size of a square block of text.

src/Core/src/[Microsoft.Maui.Graphics]/Gtk/TextExtensions.cs

@@ -30,21 +30,32 @@ public static double GetLineHeigth(this Pango.Layout layout, int numLines, bool
 
 		public static (int width, int height) GetPixelSize(this Pango.Layout layout, string text, double desiredSize = -1d, bool heightForWidth = true)
 		{
+			layout.SetText(text);
 			desiredSize = double.IsInfinity(desiredSize) ? -1 : desiredSize;
 
 			if (desiredSize > 0)
 			{
 				if (heightForWidth)
 				{
-					layout.Width = desiredSize.ScaledToPango();
+					if (desiredSize > 1)
+						layout.Width = desiredSize.ScaledToPango();
+					else
+					{
+						// This means layout requested desired size with constraints (0, infinity).
+						// Instead of trying to fit the text by splitting it into as many lines as possible,
+						// try to approximate size of a square block of text.
+						layout.Width = -1;
+						layout.GetPixelSize(out var singleLineWidth, out var singleLineHeight);
+						var approximateWidth = Math.Sqrt(singleLineWidth / (singleLineHeight + 1)) * singleLineHeight;
+						layout.Width = approximateWidth.ScaledToPango();
+					}
 				}
 				else
 				{
 					layout.Height = desiredSize.ScaledToPango();
 				}
 			}
 
-			layout.SetText(text);
 			layout.GetPixelSize(out var textWidth, out var textHeight);
 
 			return (textWidth, textHeight);