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/0880-Add-entity-knockback-API.patch

@@ -0,0 +1,22 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: MelnCat <melncatuwu@gmail.com>
+Date: Sun, 16 Oct 2022 12:10:17 -0700
+Subject: [PATCH] Add entity knockback API
+
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java
+index d15a252285e10ce062319b0f1051f59ba46701a0..351869735644c984090e1ac571b5ff118ecae9bc 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java
+@@ -995,5 +995,11 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
+         }
+         throw new IllegalArgumentException(entityCategory + " is an unrecognized entity category");
+     }
++
++    @Override
++    public void knockback(double strength, double directionX, double directionZ) {
++        Preconditions.checkArgument(strength > 0, "Knockback strength must be > 0");
++        getHandle().knockback(strength, directionX, directionZ);
++    };
+     // Paper end
+ }