Added roles (may or may not be used)

dotnet/AipsCore/Domain/Models/User/External/UserRole.cs

@@ -0,0 +1,26 @@
+using AipsCore.Domain.Common.Validation;
+using AipsCore.Domain.Models.User.Validation;
+
+namespace AipsCore.Domain.Models.User.External;
+
+public record UserRole
+{
+    public string Name { get; init; }
+
+    private UserRole(string Name)
+    {
+        this.Name = Name;
+    }
+    
+    public static UserRole User => new("User");
+    public static UserRole Admin => new("Admin");
+    
+    public static IEnumerable<UserRole> All() => [User, Admin];
+
+    public static UserRole FromString(string name)
+    {
+        var role = All().FirstOrDefault(r => r.Name.Equals(name, StringComparison.OrdinalIgnoreCase));
+        
+        return role ?? throw new ValidationException(UserErrors.RoleDoesNotExist(name));
+    }
+}