Added OpenID endpoints tests and documentation

docs/models.md

@@ -81,3 +81,17 @@ public class UserCreator {
 ```csharp
 public interface IPermissionOwner;
 ```
+
+## SingleValueResult
+```csharp
+public struct SingleValueResult<TValue>(TValue value) {
+    public TValue Value { get; set; } = value;
+}
+```
+
+## UserPasswordValidation
+```csharp
+public sealed class UserPasswordValidation {
+    public string Password { get; set; }
+}
+```