Added trivial IdentityStringParser to provider in order to complete the logic

Author: ajgorhoe

src/IGLib.Core/Console/Validation/Implementations/StringParsing/StringParserProvider.cs

@@ -20,9 +20,13 @@ public static IStringParser<T> GetParser<T>(IFormatProvider? formatProvider = nu
 
         private static object GetParser(Type targetType, IFormatProvider formatProvider)
         {
+            if (targetType == typeof(string))
+                return new IdentityStringParser();
 
-            throw new NotImplementedException();
 
+
+            throw new NotSupportedException(
+                $"No built-in string parser is available for target type '{targetType.FullName}'.");
         }
 
     }