feat: Implement ServiceFactory for dependency injection

- Added ServiceFactory class to manage service registrations and service provider creation.
- Implemented a lazy-loaded IServiceProvider to ensure services are only built once.
- Prevent further modifications to the service collection after the service provider is created.
- Added Provide<T>() method to resolve and retrieve services from the service provider.

DigitalData.Core.Client/BaseHttpClientService.cs

@@ -44,7 +44,10 @@ namespace DigitalData.Core.Client
             if (sendWithCookie)
             {
                 var cookieHeader = _cookies.GetCookieHeader(requestUri);
-                requestMessage.Headers.Add("Cookie", cookieHeader);
+                if (!string.IsNullOrWhiteSpace(cookieHeader))
+                {
+                    requestMessage.Headers.Add("Cookie", cookieHeader);
+                }
             }
 
             // Add body content if provided