Jupyterlab-code-formatter

**General**

- Major refactor of repo, now based off the update jupyterlab extension cookiecutter;
- Introduce an actually working dockerised dev env;

**Server extension**

- Add `ruff` support - courtesy of felix-cw;

**Jupyterlab extension**

- Add `ruff` support - courtesy of felix-cw;

**Server extension**

- Use `importlib` instead of `pkg_resources` which is being deprecated;

**Server extension**

- Swap importable check to something more performant - courtesy of krassowski;

**Jupyterlab extension**

- Add more isort configuration settings - courtesy of dcnadler;

**Server extension**

- Remove implicit dependency of `which` binary - courtesy of KanchiShimono;

**Server extension**

- Add `AStyle` support using `subprocess - courtesy of nthiery;

**General**

- Add `rustfmt` support using `subprocess` - courtesy of andrelfpinto;
- Add docs for adding a custom formatter;

**Server extension**

- Handle single/double leading question mark properly;
- Re-add trailing new line if not in notebook;

**Jupyterlab extension**

- Suppress cell skipped error properly if configured to suppress;