Bumper set of many changes

[stwalkerster]

This pull request is a bumper set of changes which fix several aspects of Overviewer, and add support for other functionality.

At a high-level overview, this includes changes for the following:

• A bunch of general cleanup around things being rendered in odd places (eg reinforced deepslate, froglights, suspicious sand, etc being treated as wood), removal of a whole bunch of unnecessarily-duplicated code (eg, calibrated sculk sensors)
• Fixes for some leaves rendering with biome colours incorrectly (eg, birch/spruce incorrectly taking biome colours)
• Adding support for hanging signs on a wall and hanging below a block, decorated pots, big dripleaves
• Adding support for display of chiseled bookshelf states
• Fixes to various textures (bamboo signs which use a completely different texture to other signs, wet sponges, double stone slabs) and some blocks not correctly being treated as transparent
• Performance enhancements for genPOI caused by Overviewer unnecessarily parsing all the block state data
• Stop treating DIM0 as special, enabling adding support for reading entities from the separate .mca files (fixes #20)
• Adding support for changing how POIs are rendered in CSS, including allowing filter functions access to the unwrangled raw JSON text format
• Fixes to allow querying sign text colour and glow state on legacy-format signs using the new format (extends fix from 0d7b664d1e1d5f542f5944bd50dfd209a14cd196)
• Fix double UTF-16/UTF-8 encoding on NBT data, allowing emojis on signs to render correctly
• Add the new 1.21 blocks currently available in the experimental datapack. The Vault is configured as a block ID with a render function, but it currently doesn't render anything as the texture is only currently present in Minecraft snapshots. I already have code to do the rendering, but it's not part of this PR.

Some assorted screenshots:

Crafter + Trial Spawner: Chiseled Copper + Copper Grate: Copper Bulb: Doors + Trapdoors:

All the new Tuff variant blocks:

The following screenshots are highly-dependent on configuration, but illustrate what is now possible with the relevant configuration: