Chunk debug command (#2118)

* Chunk debug command

Prints all chunk information to a text file into the debug
folder in the root server folder.

Will output server version and all online players to the
file as well. We do not log anything but the location,
world and username of the player.

Also logs the value of these config values (note not all are paper's):
- keep spawn loaded value
- spawn radius
- view distance

Each chunk has the following logged:
- Coordinate
- Ticket level & its corresponding state
- Whether it is queued for unload
- Chunk status (may be unloaded)
- All tickets on the chunk

Example log:
https://gist.github.com/Spottedleaf/203bd211020a3a04da0e574fb57dab45

For references on certain keywords (ticket, status, etc), please see:

https://bugs.mojang.com/browse/MC-141484?focusedCommentId=528273&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-528273
https://bugs.mojang.com/browse/MC-141484?focusedCommentId=528577&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-528577

* Use JSON for the chunk dump

* Fix obfhelper naming

* Fix incorrect JSON spec

Spigot-Server-Patches/MC-Dev-fixes.patch

@@ -470,6 +470,19 @@ index 41a5d1dc29..b3799ab564 100644
              acompletablefuture[i] = completablefuture1.whenComplete((object, throwable) -> {
                  if (throwable != null) {
                      completablefuture.completeExceptionally(throwable);
+diff --git a/src/main/java/net/minecraft/server/Ticket.java b/src/main/java/net/minecraft/server/Ticket.java
+index fc8cd29739..74d6e3d2f5 100644
+--- a/src/main/java/net/minecraft/server/Ticket.java
++++ b/src/main/java/net/minecraft/server/Ticket.java
+@@ -0,0 +0,0 @@ public final class Ticket<T> implements Comparable<Ticket<?>> {
+         } else {
+             int j = Integer.compare(System.identityHashCode(this.a), System.identityHashCode(ticket.a));
+ 
+-            return j != 0 ? j : this.a.a().compare(this.c, ticket.c);
++            return j != 0 ? j : this.a.a().compare(this.c, (T)ticket.c); // Paper - decompile fix
+         }
+     }
+ 
 diff --git a/src/main/java/net/minecraft/server/VillagerTrades.java b/src/main/java/net/minecraft/server/VillagerTrades.java
 index 73f9da1fdb..2a4e4f7859 100644
 --- a/src/main/java/net/minecraft/server/VillagerTrades.java