refactor(ll): adapt the fuse-abi crate

[mkroening]

Hi there,

I have published the fuse-abi crate for autogenerated, up-to-date bindings to FUSE devices, which is also usable in no_std environments such as OS kernels.

This initial unclean port of fuser to fuse-abi seems to work in practice, according to CI.
The most important difference to fuser::ll::fuse_abi is that the crate's struct's fields are not feature-gated. This would require fuser to adapt another approach to access to versioned fields which change the struct's size. This does not happen a lot, but there are cases such as with fuse_mknod_in, which libfuse handles like this.

If you are open to such an approach or have another idea to this issue, I'd be happy to continue working on this. I just wanted to test the waters before putting in more work. :)

[cberner]

I prefer to minimize the number of dependencies in my crates, so don't want to merge this. Looks neat though, thanks for submitting!