huak fmt --check will exit early if imports aren't sorted

[cnpryer]

In order to check both imports and the rest of Python source code, huak uses ruff and black. In the future, ideally, only ruff will be necessary. Otherwise better process management could resolve this.

If --check is passed to huak fmt, huak will first run the ruff check on the imports. huak will emit a warning about this issue prior to running the check. At the moment if non-zero exit codes are returned from these commands, huak exits immediately with the code. This means the black check won't run if ruff exits with non-zero.