Update upstream BD/B/CB/S

Note to other developers: This commit may require you to wipe your
workspace as a result of the changes to BD.

--- work/BuildData
Submodule work/BuildData f527a8ff..d56672db:
  > Mappings Update

--- work/Bukkit
Submodule work/Bukkit 0c1d258bb..db06c80d7:
  > Add list of entities to EntityTransformEvent
  > SPIGOT-4347: Add API to allow storing arbitrary values on ItemStacks

---work/CraftBukkit
Submodule work/CraftBukkit 6a398ac44..068dab5be:
  > Enable optional source JAR shading via profile shadeSourcesJar
  > Use ImmutableList rather than AbstractList for CraftMetaBook
  > Fix setRecipes(List) not setting Knowledge Book recipes.
  > Mappings Update
  > Add list of entities to EntityTransformEvent & move die calls
  > SPIGOT-4347: Add API to allow storing arbitrary values on ItemStacks
  > Add Vanilla help to default permissions

--- work/Spigot
Submodule work/Spigot a1f2566f6..e769fe4d9:
  > Mappings Update
  > Rebuild patches

Spigot-Server-Patches/Allow-specifying-a-custom-authentication-servers-dow.patch

@@ -27,7 +27,7 @@ index 963096fb3..a499578db 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/LoginListener.java b/src/main/java/net/minecraft/server/LoginListener.java
-index 8bbea9624..10c82107d 100644
+index 90d1096e5..b682b3a43 100644
 --- a/src/main/java/net/minecraft/server/LoginListener.java
 +++ b/src/main/java/net/minecraft/server/LoginListener.java
 @@ -0,0 +0,0 @@ public class LoginListener implements PacketLoginInListener, ITickable {
@@ -39,6 +39,6 @@ index 8bbea9624..10c82107d 100644
 +                                LoginListener.this.disconnect(new ChatComponentText(com.destroystokyo.paper.PaperConfig.authenticationServersDownKickMessage));
 +                            } else // Paper end
                              LoginListener.this.disconnect(new ChatMessage("multiplayer.disconnect.authservers_down", new Object[0]));
-                             LoginListener.c.error("Couldn\'t verify username because servers are unavailable");
+                             LoginListener.c.error("Couldn't verify username because servers are unavailable");
                          }
 --