Use ArgumentNullException.ThrowIfNull in ChecksumValidator (#46174)

Author: javiercn

src/Mvc/Mvc.Razor.RuntimeCompilation/src/ChecksumValidator.cs

@@ -93,10 +93,7 @@ public static bool IsItemValid(RazorProjectFileSystem fileSystem, RazorCompiledI
 
     private static (byte[] checksum, string algorithm) ComputeChecksum(RazorProjectItem projectItem, string checksumAlgorithm)
     {
-        if (projectItem == null)
-        {
-            throw new ArgumentNullException(nameof(projectItem));
-        }
+        ArgumentNullException.ThrowIfNull(projectItem);
 
         Func<Stream, byte[]> hashData;
         string algorithmName;