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

CaddyManager.Contracts/Configurations/Docker/DockerServiceConfiguration.cs

@@ -0,0 +1,32 @@
+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;
+        }
+    }
+}