Put the component in a Pin<>

Removed the drop and create from the ComponentVTable:
since we are not using VBox<ComponentVTable>, this simplifies a bit
the code of the interpreter and everything else.

But there is still a lot of changes everywhere to support that the Component
is pinned.
This is just for the component. Which would be required if later we want
to access the properties as Pin<Property<_>>. But we have not yet ability
to do projections

api/sixtyfps-cpp/include/vtable.h

@@ -13,6 +13,9 @@ using VRef = VRefMut<T>;
 template<typename T>
 using VBox = VRefMut<T>;
 
+template<typename T>
+using Pin = T;
+
 /*
 template<typename T>
 struct VBox {