Drop manual isEditable copy in CraftSign

Signs no longer have a specific isEdiable state, the entire API in this
regard needs updating/deprecation. The boolean field is completely gone,
replaced by a uuid (which will need a new setEditingPlayer(UUID) method
on the Sign interface), and the current upstream implementation of
setEdiable simply flips the is_waxed state.

This patch is hence not needed as it neither allows editing (which will
be redone in a later patch) nor is required to copy the is_waxed boolean
flag as it lives in the signs compound tag and is covered by applyTo.

patches/server/0819-Add-PlayerStopUsingItemEvent.patch

@@ -1,18 +0,0 @@
-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: u9g <git@u9g.dev>
-Date: Tue, 3 May 2022 20:41:37 -0400
-Subject: [PATCH] Add PlayerStopUsingItemEvent
-
-
-diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
-index c629e03d5281e566050ca22d2c3a16626f7a57cc..9ee16dc1f425e4f0795eec3dcc18affc70e85a31 100644
---- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
-+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
-@@ -3967,6 +3967,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
- 
-     public void releaseUsingItem() {
-         if (!this.useItem.isEmpty()) {
-+            if (this instanceof ServerPlayer) new io.papermc.paper.event.player.PlayerStopUsingItemEvent((Player) getBukkitEntity(), useItem.asBukkitMirror(), getTicksUsingItem()).callEvent(); // Paper
-             this.useItem.releaseUsing(this.level(), this, this.getUseItemRemainingTicks());
-             if (this.useItem.useOnRelease()) {
-                 this.updatingUsingItem();