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

CaddyManager.Contracts/Configurations/IConfigurationsService.cs

@@ -0,0 +1,18 @@
+using CaddyManager.Contracts.Configurations.Caddy;
+using CaddyManager.Contracts.Configurations.Docker;
+
+namespace CaddyManager.Contracts.Configurations;
+
+/// <summary>
+/// Contract for the services providing the configurations for the application
+/// </summary>
+public interface IConfigurationsService
+{
+    /// <summary>
+    /// Method extracting the configurations from the appsettings.json file or environment variables base on the
+    /// type of the configuration class to determine the section name
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    /// <returns></returns>
+    T Get<T>() where T : class;
+}