chore: update project structure with contracts and services for CaddyManager, including configuration and Docker integration

CaddyManager.Contracts/Configurations/Caddy/CaddyServiceConfigurations.cs

@@ -0,0 +1,11 @@
+namespace CaddyManager.Contracts.Configurations.Caddy;
+
+/// <summary>
+/// Wraps the configurations for Caddy service
+/// </summary>
+public class CaddyServiceConfigurations
+{
+    public const string Caddy = "Caddy";
+    
+    public string ConfigDir { get; set; } = "/config";
+}