Storage/Filesystem code?

[vbe0201]

Since RCM payloads are limited in size, it wouldn't make much sense to try to fit everything, including future crates and changes, into it.

Thus, we need the functionality to

• mount and unmount SD cards

• read/write files

• process those in Rust code

and the same aspects for the Switch's internal storage, the eMMC.

This is probably out of scope for libswitch as it isn't totally Switch/Tegra210-related so a separate crate with no_std capability would be adequate.

Thus, we don't have std::fs and need a partial replacement for it. Since Switch only supports Fat32 and exFat by extension, https://github.com/sunriseos/libfat can be used for that. It doesn't support exFat, but this isn't high priority for now.

Once this is implemented, it can be used for chainloading from the SD card.