each1<T1 extends Component> method
Iterates (entity, T1) for every entity with a T1 component. Inspired
by Bevy's Query<&T>.
Implementation
Iterable<(WorldEntity, T1)> each1<T1 extends Component>() sync* {
for (final entity in withComponent<T1>()) {
if (_readComponent<T1>(entity) case Some(value: final v)) {
yield (entity, v);
}
}
}