added docker instance manager constructor

instance_manager/docker/instance_manager.go

@@ -552,3 +552,17 @@ func (self *InstanceManager) StopFileBrowser(ctx context.Context, serverId strin
 
 	return nil
 }
+
+func NewInstanceManager(config models.DockerInstanceManagerConfig) (*InstanceManager, error) {
+	apiClient, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
+	if err != nil {
+		return nil, err
+	}
+
+	defer apiClient.Close()
+
+	return &InstanceManager{
+		config: config,
+		client: *apiClient,
+	}, nil
+}