Automerge CLI depends transitively (via and old version of `clap` and
via `colored_json` on `atty` and `ansi_term`. These crates are both
marked as unmaintained and this generates irritating `cargo deny`
messages. To avoid this, implement colored JSON ourselves using the
`termcolor` crate - colored JSON is pretty mechanical. Also update
criterion and cbindgen dependencies and ignore the criterion tree in
deny.toml as we only ever use it in benchmarks.
All that's left now is a warning about atty in cbindgen, we'll just have
to wait for cbindgen to fix that, it's a build time dependency anyway so
it's not really an issue.
After some discussion with PVH I realise that the repo structure in the
last reorg was very rust-centric. In an attempt to put each language on
a level footing move the rust code and project files into ./rust
