PM-7746 Added specific validation messages for (non) privileged apps validation on Fido2 flows. Also fixed typo on "privileged" and updated UT (#3198)

src/Core/Exceptions/ValidationException.cs

@@ -0,0 +1,10 @@
+namespace Bit.Core.Exceptions
+{
+    public class ValidationException : Exception
+    {
+        public ValidationException(string localizedMessage)
+            : base(localizedMessage)
+        {
+        }
+    }
+}