* Replace BlockStates reading with new 1.16 logic
* Account for running on older platforms
Splits out the new reading to AnvilChunk16, uses data version to detect
the appropriate version.
* Move data versions to Constants
Also fixes some logic hiccups that become obvious with the new names.
* Fix LegacyMapper DFU handling
* Fix factor indexing
(cherry picked from commit 8c171f0929e8530aab1731d122649adc58c5161f)