Make Roles property non-nullable with empty array default in settings classes

Co-authored-by: marcominerva <3522534+marcominerva@users.noreply.github.com>

Author: Copilot

src/SimpleAuthentication.Abstractions/ApiKey/ApiKeySettings.cs

@@ -46,7 +46,7 @@ public class ApiKeySettings : AuthenticationSchemeOptions
     /// </summary>
     /// <seealso cref="ApiKeyValue"/>
     /// <seealso cref="UserName"/>
-    public IEnumerable<string>? Roles { get; set; }
+    public IEnumerable<string> Roles { get; set; } = [];
 
     private ICollection<ApiKey> apiKeys = [];
     /// <summary>

src/SimpleAuthentication.Abstractions/BasicAuthentication/BasicAuthenticationSettings.cs

@@ -35,7 +35,7 @@ public class BasicAuthenticationSettings : AuthenticationSchemeOptions
     /// </summary>
     /// <seealso cref="UserName"/>
     /// <seealso cref="Password"/>
-    public IEnumerable<string>? Roles { get; set; }
+    public IEnumerable<string> Roles { get; set; } = [];
 
     private ICollection<Credential> credentials = [];
     /// <summary>