Added enterprise attestation (#410)

Author: abergs

Demo/Pages/_options.cshtml

@@ -15,6 +15,7 @@
                                 <option selected value="none">None</option>
                                 <option value="indirect">Indirect</option>
                                 <option value="direct">Direct</option>
+                                <option value="enterprise">Enterprise</option>
                             </select>
                         </div>
                     </div>

Src/Fido2.Models/Objects/AttestationConveyancePreference.cs

@@ -27,5 +27,11 @@ public enum AttestationConveyancePreference
     /// This value indicates that the Relying Party wants to receive the attestation statement as generated by the authenticator.
     /// </summary>
     [EnumMember(Value = "direct")]
-    Direct
+    Direct,
+    
+    /// <summary>
+    /// This value indicates that the Relying Party wants to receive an attestation statement that may include uniquely identifying information.
+    /// </summary>
+    [EnumMember(Value ="enterprise")]
+    Enterprise
 }