* fix: improve biome setting to avoid writing directly to chunk
- Removes possibility of writing to the LevelChunkSection biomes PalettedContainer whilst it is being read for sending packets
- I believe this occured mostly on clipboard operations where blocks are written before biomes, so chunks are being sent whilst writing biomes
- This would explain why the error reported in the below issue (and others) is/was so rare
- Of course I could be completely wrong about all of this, but given the line in LevelChunkSection#write that the error seems to consistently occur on is when writing biomes to the packet, and that the only place I can find in FAWE where we write to a "live" PalettedContainer is for biomes, I am reasonably confident that this is the cause
- Should address #2729
* Remove self-refraction-check
- remove ChunkHolder locking concept as this is no longer needed
- previously we obtained the copy from chunk GET on finalize, meaning the copy could be replaced by a "newer" one (bad)
- work around this issue by introducing concept of "unique" keys to map chunk GET copies to
- correctly handle resetting of various chunk-related classes to actually allow pooling to work
- remove chunks as they are submitted when flushing a SingleThreadQueueExtenting
