Carpet LAB Addition

Carpet features created for the LAB SMP, as we need them. Currently only contains Scarpet events.

Scarpet events:

__on_player_message_broadcast(player, message)

• Triggers right before a player message is broadcasted to the server.
• Can be cancelled by returning 'cancel', which prevents the message from being sent.
• Useful for making changes to chats before they're sent.

__on_player_edits_sign(player, block)

• Fires after a player edits a sign, after the vanilla text changes take place.
• Can be used to add custom sign formatting.
• Example script