[Feature] Implement xymb linear region file format

[sofianedjerbi]

Allow user to choose between anvil (zlib) region file format and linear (zstd) region file format.
Up to 50% less disk space for OW and Nether
Up to 95% less disk space for The End
Source patch
Documentation
I'll send a PR ASAP

[sofianedjerbi]

Done
f659c93

[IPECTER]

Im makig Fusion reads both "mca" and "linear" all the time. (without any configurable thing)
Configurable thing is only save-format.