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

CaddyManager.Contracts/Configurations/Caddy/CaddyServiceConfigurations.cs

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+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";
+}

CaddyManager.Contracts/Configurations/Docker/DockerServiceConfiguration.cs

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+namespace CaddyManager.Contracts.Configurations.Docker;
+
+/// <summary>
+/// Configuration for the Docker service
+/// </summary>
+public class DockerServiceConfiguration
+{
+    public const string Docker = "Docker";
+
+    /// <summary>
+    /// Name of the Caddy container to be controlled (i.e restart)
+    /// </summary>
+    public string CaddyContainerName { get; set; } = "caddy";
+    
+    /// <summary>
+    /// Uri to the Docker host
+    /// </summary>
+    public string DockerHost { get; set; } = "unix:///var/run/docker.sock";
+    
+    /// <summary>
+    /// Returns the Docker host with environment check. If the environment variable DOCKER_HOST is set, it will return
+    /// that value, otherwise it will return the value of DockerHost
+    /// </summary>
+    public string DockerHostWithEnvCheck
+    {
+        get
+        {
+            var envValue = Environment.GetEnvironmentVariable("DOCKER_HOST");
+            return string.IsNullOrWhiteSpace(envValue) ? DockerHost : envValue;
+        }
+    }
+}

CaddyManager.Contracts/Configurations/IConfigurationsService.cs

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+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;
+}