Migrate GD code to module

Test: atest --host bluetooth_test_gd
Change-Id: Ibcb219666ff5552efc602bf063e69a6e6b7e4bd8
diff --git a/gd/module.h b/gd/module.h
index 2e78bca..a073649 100644
--- a/gd/module.h
+++ b/gd/module.h
@@ -90,6 +90,13 @@
   // in dependency order
   void Start(ModuleList* modules);
 
+  template <class T>
+  void Start() {
+    Start(&T::Factory);
+  }
+
+  void Start(const ModuleFactory* id);
+
   // Stop all running modules in reverse order of start
   void StopAll();