GH-1298 Add tpa event api

[vLuckyyy]

No description provided.

[gemini-code-assist]

Code Review

This pull request introduces a new API for teleportation request events (PreTeleportRequestEvent and TeleportRequestEvent) and integrates them into the existing tpa and tpahere commands. The changes are logical and the new event API is well-defined.

However, I've found a few issues:

• There are duplicate registrations of a command and a listener in the example plugin, which could lead to bugs.
• More critically, there are several instances where a synchronous Bukkit event is being called from an asynchronous thread. This is a significant threading issue that can cause server instability and must be addressed.

My review includes detailed comments on these points with suggestions for how to resolve them.

[Jakubk15]

Why is there a need to explicitly declare final?

Suggested change

	final Player sender = event.getSender();
	final Player target = event.getTarget();
	Player sender = event.getSender();
	Player target = event.getTarget();

[Rollczi]

trzeba te eventy ogarnąć bo one są wołane async, a deklaracja jest false w konstruktorze - pytanie czy w sumie chcemy async może wolimy to sync dać

[Jakubk15]

???

Suggested change

	/*
	if (!countryService.areInSameCountry(sender, target)) {
	sender.sendMessage("You are not in the same country!");
	event.setCancelled(true);
	}
	*/