Changes in this commit:
- Adds transport API `fs_hashfile` to compute the hash of a file with given
algorithm.
- Adds commands `mpremote <...>sum file` to compute and print hashes of
various algorithms.
- Adds shortcut `mpremote sha256sum file`.
- Uses the hash computation to improve speed of recursive file copy to
avoid copying a file where the target is identical.
For recursive copy, if possible it will use the board's support (e.g.
built-in hashlib or hashlib from micropython-lib), but will fall back to
downloading the file and using the local implementation.
This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Signed-off-by: Damien George <damien@micropython.org>