[Test Only] Port the Idna test fixes to support Unicode 15 (#110705)

Author: tarekgh

src/libraries/System.Globalization.Extensions/tests/IdnMapping/Data/Factory.cs

@@ -26,7 +26,9 @@ private static string RemoveComment(string line)
         private static Stream GetIdnaTestTxt()
         {
             string fileName = null;
-            if (PlatformDetection.ICUVersion >= new Version(66, 0))
+            if (PlatformDetection.ICUVersion >= new Version(74, 0))
+                fileName = "IdnaTest_15_1.txt";
+            else if (PlatformDetection.ICUVersion >= new Version(66, 0))
                 fileName = "IdnaTest_13.txt";
             else if (PlatformDetection.IsWindows7)
                 fileName = "IdnaTest_Win7.txt";
@@ -61,7 +63,9 @@ private static IEnumerable<IConformanceIdnaTest> ParseFile(Stream stream, Func<s
 
         private static IConformanceIdnaTest GetConformanceIdnaTest(string line, int lineCount)
         {
-            if (PlatformDetection.ICUVersion >= new Version(66, 0))
+            if (PlatformDetection.ICUVersion >= new Version(74, 0))
+                return new Unicode_15_1_IdnaTest(line, lineCount);
+            else if (PlatformDetection.ICUVersion >= new Version(66, 0))
                 return new Unicode_13_0_IdnaTest(line, lineCount);
             else if (PlatformDetection.IsWindows7)
                 return new Unicode_Win7_IdnaTest(line, lineCount);