All Require Components should be inserted first, and then the on_add Hook should be executed.

[qpshot]

Currently, in Bevy, Require Components will override the components added within the on_add hook, so we can't use the require macro to add components that we want to initialize. This leads to two issues:

1. It becomes hard to easily see which components were added to the entity by the on_add hook.
2. We need to check within the hook whether the entity already has the components that need initialization, which increases boilerplate code.

Current Bevy

#[derive(Default, Component)]
#[component(on_add = init_i18n_text)]
pub struct I18nText {
    key: String,
}
fn init_i18n_text (
){
    if let Some(mut text) = world.get_mut::<Text>(entity) {
         todo!();
    } else {
        world
            .commands()
            .entity(entity)
            .insert(Text::new(todo!();));
    }

}

This suggestion

#[derive(Default, Component)]
#[require(Text)]
#[component(on_add = init_i18n_text)]
pub struct I18nText {
    key: String,
}
fn init_i18n_text (
){
    let mut text = world.get_mut::<Text>(entity).unwrap();
    todo!();
}