Road to Minecraft 1.21

[theogiraudet]

This issue tracks all of the breaking changes Minecraft is introducing in the 1.21 release, which need to be considered in this new Bookshelf release. If you find any breaking changes that can break Bookshelf that are not listed here, please add them by commenting on the issue.

Breaking changes:

• [ ] The folders tags/blocks, tags/functions are renamed to tags/block, tags/function.
• [ ] The folder loot_tables, functions, predicates, structures, advancements are renamed to loot_table, function, predicate, structure, advancement.
• [ ] New blocks and blockstates.

Optimisations:

• [ ] Replace all @e[limit=1, sort=nearest] to @n.