Support required components which have no sensible default

[teohhanhui]

What problem does this solve or what need does it fill?

Required components spawns required components using the Default implementation, or a default specified in the #[require(...)] attribute.

I'd like to have a way to force the caller to provide some required components at spawn time.

What solution would you like?

Maybe something like:

#[require(Team)]
#[must_provide(Team)]
struct Player {
    // ...
}

What alternative(s) have you considered?

1. Continue using bundles.

2. Add the required component as a field on the "concept component".

   From the general design guidelines:

   2. Prefer using component fields directly on the "concept component" as the "public API" for the feature.

   3. Prefer simple APIs / don't over-componentize. By default, if you need to attach new properties to a concept, just add them as fields to that concept's component.

   However, there's unfortunately no way to query by component field from the ECS, AFAICT...

Additional context

N/A

[hukasu]

#16267 has some extra ideas for required components

[teohhanhui]

Duplicate of #16194