Allowing for using named entity modifiers together with switchable tags

[jtferson]

Describe the problem you are trying to solve.
Currently we can match against regular entities with switchable tags but narrowing that down to just singleton or specific entities is not possible. It might be useful to have such matching logic in order to have global state machines.

Describe the solution you'd like
The query signature that contains switchable tags with named modifiers properly matches:

auto Slow = ecs.entity("Slow");
auto Normal = ecs.entity("Normal");
auto Fast = ecs.entity("Fast");
auto GlobalSpeed = ecs.type("GlobalSpeed", "Slow, Normal, Fast");
	
ecs.entity("GameArena")
    .add_switch(GlobalSpeed)
    .add_case(Slow);

ecs.query<>("Position, Velocity, GameArena:CASE | Slow").iter([&](flecs::iter& It)
{
});