Waystones

- Fixed distance being displayed wrongly in waystone selection and `/waystones list` command
- Data Packs: Added `has_structure/deepslate_waystone` tag and generation logic
  - However, waystones still won't generate in the Deep Dark as this is not supported by the default placement modifier.
  - Additionally, use of these tags is at your own risk. Vanilla generation is very fickle and it's recommended to use something like Lithostitched to add waystone generation to other biomes instead.
- Data Packs: Fixed `waystones:waystone` placement modifier only respecting dimension ceilings in the Nether
  - Same disclaimer as above.