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/Expose-client-protocol-version-and-virtual-host.patch

@@ -11,7 +11,7 @@ Add a NetworkClient interface that provides access to:
 
 diff --git a/src/main/java/com/destroystokyo/paper/network/NetworkClient.java b/src/main/java/com/destroystokyo/paper/network/NetworkClient.java
 new file mode 100644
-index 000000000..7b2af1bd7
+index 00000000..7b2af1bd
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/network/NetworkClient.java
 @@ -0,0 +0,0 @@
@@ -57,7 +57,7 @@ index 000000000..7b2af1bd7
 +
 +}
 diff --git a/src/main/java/org/bukkit/entity/Player.java b/src/main/java/org/bukkit/entity/Player.java
-index 290b9d75d..d8cc7d5db 100644
+index f14bdd22..f0aee351 100644
 --- a/src/main/java/org/bukkit/entity/Player.java
 +++ b/src/main/java/org/bukkit/entity/Player.java
 @@ -0,0 +0,0 @@ import org.jetbrains.annotations.Nullable;