Add "index" dependet overrides for createMany/makeMany #170
Description
It would be super helpful if I could createMany or makeMany with e.g. some kind of callback which passes the element number being created. This could easily allow seeding multiple entities with (simple) state differences
// Example 1: Seeding users, where some of them should not be active:
new UserFactory().createMany(10, (index: number) => ({ isActive: Boolean(index % 3) }));
// Example 2: Seeding products, with a "unnatural" order in database:
new ProductFactory().createMany(10, (index: number) => ({ order: 10 - (index % 5) }));