Implement pressure plate activation logic and events (#5991)

closes #5936

This implements all of the basic activation logic for pressure plates.
It also introduces a PressurePlateUpdateEvent, which is called in pulses when entities are standing on top of the plate and when it deactivates. Deactivation can be detected by checking if the list of activating entities is empty.

---------

Co-authored-by: Javier León <58715544+JavierLeon9966@users.noreply.github.com>

src/event/block/PressurePlateUpdateEvent.php

@@ -0,0 +1,53 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+ */
+
+declare(strict_types=1);
+
+namespace pocketmine\event\block;
+
+use pocketmine\block\Block;
+use pocketmine\entity\Entity;
+use pocketmine\event\Cancellable;
+
+/**
+ * Called whenever the list of entities on a pressure plate changes.
+ * Depending on the type of pressure plate, this might turn on/off its signal, or change the signal strength.
+ */
+final class PressurePlateUpdateEvent extends BaseBlockChangeEvent implements Cancellable{
+	/**
+	 * @param Entity[] $activatingEntities
+	 */
+	public function __construct(
+		Block $block,
+		Block $newState,
+		private array $activatingEntities
+	){
+		parent::__construct($block, $newState);
+	}
+
+	/**
+	 * Returns a list of entities intersecting the pressure plate's activation box.
+	 * If the pressure plate is about to deactivate, this list will be empty.
+	 *
+	 * @return Entity[]
+	 */
+	public function getActivatingEntities() : array{ return $this->activatingEntities; }
+}