Quite a lot of changes, but I was too lazy to split them in different commits (and they'll be squashed later anyway):
* Floodgate plugin message channels are now registered (because Spigot requires that, and I guess it's better practice)
* Updated the Statistics form to match the new Forms API
* The common jar is now much smaller, because Jackson isn't needed anymore in the common module
* Fixed some bugs in Forms where empty fields would lead to excluding them in the serialization (making Bedrock complain)
And a few other things, like a new boolean in RawSkin saying if the Skin is an Alex or Steve model.
The normal identity UUID caused problems and caused the bedrock client to crash when using Floodgate. This was likely because on bedrock edition, it's a version 3 UUID opposed to java edition which uses version 4.
