Added FormatProviderDefaults, a simplified approach to select the default IFormatProvider when not specified

Author: ajgorhoe

src/IGLib.Core/Console/Validation/DefaultFormatProvider/Simple/FormatProviderDefaults.cs

@@ -0,0 +1,22 @@
+
+using System;
+using System.Globalization;
+
+namespace IGLib;
+
+public static class FormatProviderDefaults
+{
+    public static IFormatProvider Global { get; private set; } = CultureInfo.InvariantCulture;
+
+    public static void SetGlobal(IFormatProvider formatProvider)
+    {
+        if (formatProvider == null)
+            throw new ArgumentNullException(nameof(formatProvider));
+
+        Global = formatProvider;
+    }
+
+    public static IFormatProvider Resolve(IFormatProvider? specifiedFormatProvider)
+        => specifiedFormatProvider ?? Global;
+}
+