bcachefs erasure coding (RAID5/6) support (EXPERIMENTAL)

configname: CONFIG_BCACHEFS_ERASURE_CODING

Linux Kernel Configuration
└─>File systems
└─>bcachefs erasure coding (RAID5/6) support (EXPERIMENTAL)
In linux kernel since version 6.1.65 (release Date: 2023-12-03)  
This enables the "erasure_code" filesysystem and inode option, which
organizes data into reed-solomon stripes instead of ordinary
replication.

WARNING: this feature is still undergoing on disk format changes, and
should only be enabled for testing purposes.