Allowing for adding owned switchables to prefabs

[jtferson]

Describe the problem you are trying to solve.
Currently, if we define switchable tags for prefabs, they don't match with the instance entities.

Describe the solution you'd like

struct IdleState { };
struct FlyingState { };
struct FightingState { };
auto ShipBehaviourType = ecs.type("ShipBehaviour");
ShipBehaviourType.add(ecs.component<IdleState>());
ShipBehaviourType.add(ecs.component<FlyingState>());
ShipBehaviourType.add(ecs.component<FightingState>());

auto ShipPrefab = ecs.prefab()
    .add<Weapon>()
    .add_switch(ShipBehaviourType)
    .add_owned(ShipBehaviourType) //<-- Set Switch as owned
    .add_case<IdleState>()
    .add_owned<IdleState>(); //<-- Set Case as owned
ecs.entity("Rocinante")
    .add_instanceof(ShipPrefab)
    .add_case<FightingState>(); //<--- Override the default case

ecs.query<>("SWITCH | FightingState, CASE | FightingState").iter([ ](flecs::iter& It)
{
    //Matches Rocinante with FightingState
});