disguise api

[yannicklamprecht]

pre hard fork PR: #10478

relates to #10584

Adds a simple disguise api that also makes sure that invalid entity data, not belonging to the type that is faked, is filtered.
It also adds a server generator module to reduce maintenance of the entity data filter.

tldr; The API provides a way to disguise any entity as another or a player with having the possibility to interact with the entity like with any others. The big advantage is that you've the whole vanilla logic and Mob Goal and Pathfinding included without hassle.

Testing the changes can be done using the following snippet:
https://gist.github.com/yannicklamprecht/639acba127a54f5617e1281f099b7aff

Effective loc:

600 loc in patches
3k+ loc generated filter classe
400 loc generator code copied from api-generator
100 loc for generating the filter class.