Make suggestion system string distance algorithm case-insensitive (#10549)

* Make string distance algoriphm case-insensitive

* Use CurrentCulture in ToUpper()

src/System.Management.Automation/utils/FuzzyMatch.cs

@@ -2,7 +2,7 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Generic;
+using System.Globalization;
 
 namespace System.Management.Automation
 {
@@ -23,7 +23,7 @@ namespace System.Management.Automation
 
 
         /// <summary>
-        /// Compute the distance between two strings.
+        /// Compute the case-insensitive distance between two strings.
         /// Based off https://www.csharpstar.com/csharp-string-distance-algorithm/.
         /// </summary>
         /// <param name="string1">The first string to compare.</param>
@@ -31,6 +31,9 @@ namespace System.Management.Automation
         /// <returns>The distance value where the lower the value the shorter the distance between the two strings representing a closer match.</returns>
         public static int GetDamerauLevenshteinDistance(string string1, string string2)
         {
+            string1 = string1.ToUpper(CultureInfo.CurrentCulture);
+            string2 = string2.ToUpper(CultureInfo.CurrentCulture);
+
             var bounds = new { Height = string1.Length + 1, Width = string2.Length + 1 };
 
             int[,] matrix = new int[bounds.Height, bounds.Width];