Per discussion at https://github.com/astral-sh/ruff/discussions/6998
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Adds a `--preview` and `--no-preview` option to the CLI for `ruff check`
and corresponding settings. The CLI options are hidden for now.
Available in the settings as `preview = true` or `preview = false`.
Does not include environment variable configuration, although we may add
it in the future.
## Test Plan
<!-- How was it tested? -->
`cargo build`
Future work will build on this setting, such as toggling the mode during
a test.
