Cleanup: Use uint8_t instead of bool and reduce calls to remove() in f_directory_remo...

Cleanup: Use uint8_t instead of bool and reduce calls to remove() in f_directory_remove().

I am now thinking that `uint8_t` is better than `bool`.
In particular, because this allows for more flags down the road without breaking API or ABI.

Simplify the logic in `f_directory_remove()` to have only a single declaration of `remove()`.