Draft: Configure ruff to lint imports

Rather than manually check that we're following conventions for imports and to avoid developers manually having to tinker formatting, let ruff do checking and fixing of import style.

We have a bit of a mix in the codebase right now; ruff's default settings produce the smallest diff, so it could be said to be the closest to what's being done right now. The second smallest diff is achieved with a single line per import.

The main changes are in the first commit (which is just one line).

The second commit auto-fixes all existing imports to follow this style.