GitLab

* Add FatFS for onboard flash use/sharing of FAT

* Move all to "fatfs" namespace

The FatFS library defines commonly used names like WORD which could conflict
with user code otherwise.

* Restyle

* FTL-based, wear-leveling FatFS with USB export

Allow using FAT filesystem with onboard flash in a safer, wear-leveled
way and to export the onboard flash to the host as a USB drive for easy
data transfer.

* Update documentation

* Fix submodule reference

* Don't spellehcek ChaN FatFS files

* Disable FTL debugging

* More codespell skips

* Move to latest SPIFTL library

* Allow using raw flash instead of FTL

* Remove unneeded static FIL 4k allocation

* Expose FAT FS format configuration options

* Update documentation

* Remove USB partial flash rewrites

* Remove unneeded dups of FatFS sources

Leave the LICENSE.md and README.md to point to upstream.

* Clean up comments