Function retroactively_add_game_profile_component 

pub fn retroactively_add_game_profile_component(
    commands: Commands<'_, '_>,
    events: MessageReader<'_, '_, AddPlayerEvent>,
    entity_uuid_index: Res<'_, EntityUuidIndex>,
)

Add a GameProfileComponent when an AddPlayerEvent is received. Usually the GameProfileComponent will be added from the ClientboundGamePacket::AddPlayer handler though.