Add more assertion tests

Author: MackinnonBuck

src/Identity/Core/src/DefaultPasskeyHandler.cs

@@ -433,7 +433,7 @@ await VerifyClientDataAsync(
             //       NOTE: We simply fail the ceremony in this case.
             if (authenticatorData.SignCount <= storedPasskey.SignCount)
             {
-                throw PasskeyException.SignCountLessThanStoredSignCount();
+                throw PasskeyException.SignCountLessThanOrEqualToStoredSignCount();
             }
         }
 

src/Identity/Core/src/PasskeyExceptionExtensions.cs

@@ -84,7 +84,7 @@ public static PasskeyException ExpectedBackupIneligibleCredential()
         public static PasskeyException InvalidAssertionSignature()
             => new("The assertion signature was invalid.");
 
-        public static PasskeyException SignCountLessThanStoredSignCount()
+        public static PasskeyException SignCountLessThanOrEqualToStoredSignCount()
             => new("The authenticator's signature counter is unexpectedly less than or equal to the stored signature counter.");
 
         public static PasskeyException InvalidAttestationObject(Exception ex)