__metadata should register function that returns type instead of literal type

Imagine case with circular dependencies

class Car {
  @Field owner: Person // !!! Error: Person is not defined.
}

class Person {
  @Field car: Car;
}

// car has owner, owner has car

Typescript metadata would be emitted here like

eg.
__metadata('design:type', Person).

As Person is injected for the first time before Person class is initialized, it will result with ReferenceError saying Person is not defined.

If it'd emit metadata like:
__metadata('design:type', () => Person)

it'd be fine.

Later on, when using Reflect.metadata, it would also need to call meta function instead of just returning the type.

If you think it's good idea, do you have any suggestions about starting point for PR that would implement this change?

Inizia tracciando il percorso del compilatore TypeScript che emette i metadati dei decorator, quindi esamina come Reflect.metadata utilizza il valore emesso. Il lavoro è completato quando l'esempio circolare Car/Person evita il ReferenceError di inizializzazione e i consumer dei metadati invocano la funzione di tipo differita; il payload non menziona file o test.