Update upstream B/CB/S

--- work/Bukkit
Submodule work/Bukkit 6eac6d70..1ef8b9d9:
  > Add Player#openBook(ItemStack) method

--- work/CraftBukkit
Submodule work/CraftBukkit 17543ecf..649921e5:
  > Add Player#openBook(ItemStack) method
  > SPIGOT-2000: Picking up items to shield slot working inconsistently when inventory is full
  > SPIGOT-5037: Player.openMerchant does not show merchant level
  > SPIGOT-5038: Inventory.getHolder returns null for wandering traders

--- work/Spigot
Submodule work/Spigot baafee91..df0eb250:
  > SPIGOT-5043: Desync if world is changed in PlayerSpawnLocationEvent
  > Rebuild patches

Implementation developer note:
This patch adds a "pre-source" patch system for fixing malformed patches
from upstream directly. This seems to keep happening so it's best we
have some way to deal with them. This system brings those issues into
our domain rather than needing to wait for upstream to fix their
malformed files.

Spigot-API-Patches/Add-player-view-distance-API.patch

@@ -5,13 +5,14 @@ Subject: [PATCH] Add player view distance API
 
 
 diff --git a/src/main/java/org/bukkit/entity/Player.java b/src/main/java/org/bukkit/entity/Player.java
-index 6568b179d..338d47205 100644
+index f5d31648..a9b11322 100644
 --- a/src/main/java/org/bukkit/entity/Player.java
 +++ b/src/main/java/org/bukkit/entity/Player.java
 @@ -0,0 +0,0 @@ public interface Player extends HumanEntity, Conversable, OfflinePlayer, PluginM
+      * @param affects Whether the player can affect mob spawning
       */
-     public void updateCommands();
- 
+     public void setAffectsSpawning(boolean affects);
++
 +    /**
 +     * Gets the view distance for this player
 +     *
@@ -25,8 +26,7 @@ index 6568b179d..338d47205 100644
 +     * @param viewDistance the player's view distance
 +     */
 +    public void setViewDistance(int viewDistance);
-+
-     // Spigot start
-     public class Spigot extends Entity.Spigot
-     {
+     // Paper end
+ 
+     /**
 --