Use UnzipEven for SearchValues<string> Teddy on Arm64 (#118110)

Author: MihaZupan

src/libraries/System.Private.CoreLib/src/System/SearchValues/Strings/Helpers/TeddyHelper.cs

@@ -211,7 +211,7 @@ public static (Vector512<byte> Result, Vector512<byte> Prev0, Vector512<byte> Pr
         // On X86, characters above 32767 are turned into 0, but we account for that by not using Teddy if any of the string values contain a 0.
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         [CompExactlyDependsOn(typeof(Sse2))]
-        [CompExactlyDependsOn(typeof(AdvSimd))]
+        [CompExactlyDependsOn(typeof(AdvSimd.Arm64))]
         public static Vector128<byte> LoadAndPack16AsciiChars(ref char source)
         {
             Vector128<ushort> source0 = Vector128.LoadUnsafe(ref source);
@@ -221,9 +221,9 @@ public static Vector128<byte> LoadAndPack16AsciiChars(ref char source)
             {
                 return Sse2.PackUnsignedSaturate(source0.AsInt16(), source1.AsInt16());
             }
-            else if (AdvSimd.IsSupported)
+            else if (AdvSimd.Arm64.IsSupported)
             {
-                return AdvSimd.ExtractNarrowingSaturateUpper(AdvSimd.ExtractNarrowingSaturateLower(source0), source1);
+                return AdvSimd.Arm64.UnzipEven(source0.AsByte(), source1.AsByte());
             }
             else
             {