Fix DecimalPropertyEditor on non-English systems (#20215)

* Directly convert from double or float when possible. Also fixes string parsing to work on all cultures. Fixes #20214

* Added unit tests to verify behaviour.

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Co-authored-by: Andy Butland <abutland73@gmail.com>

src/Umbraco.Core/PropertyEditors/DecimalPropertyEditor.cs

@@ -64,11 +64,18 @@ public class DecimalPropertyEditor : DataEditor
             => TryParsePropertyValue(editorValue.Value);
 
         private static decimal? TryParsePropertyValue(object? value)
-            => value is decimal decimalValue
-                ? decimalValue
-                : decimal.TryParse(value?.ToString(), CultureInfo.InvariantCulture, out var parsedDecimalValue)
-                    ? parsedDecimalValue
-                    : null;
+            => value switch
+            {
+                decimal d => d,
+                double db => (decimal)db,
+                float f => (decimal)f,
+                IFormattable f => decimal.TryParse(f.ToString(null, CultureInfo.InvariantCulture), NumberStyles.Any, CultureInfo.InvariantCulture, out var parsedDecimalValue)
+                        ? parsedDecimalValue
+                        : null,
+                _ => decimal.TryParse(value?.ToString(), CultureInfo.CurrentCulture, out var parsedDecimalValue)
+                        ? parsedDecimalValue
+                        : null,
+            };
 
         /// <summary>
         /// Base validator for the decimal property editor validation against data type configured values.