Command line tools

For testing over large files
There should be three subcommands for a `carbonado` bin:

- [ ] encode
- [ ] decode
- [ ] scrub

There will also need to be corresponding fs methods, which should also be exposed for embedding. Filesystem features should also be built using a conditionally-compiled feature flag.

Start by locating the `carbonado` binary entry point and the existing filesystem API. Map the requested `encode`, `decode`, and `scrub` subcommands, then determine how filesystem functionality should be conditionally compiled and exposed for embedding. Done means all three commands and corresponding filesystem methods are defined and covered by the project’s tests.

Written by the indexing model from the issue text.