Add hidden --preview / --no-preview options to ruff check (#7009)

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.

crates/ruff_wasm/src/lib.rs

@@ -128,6 +128,7 @@ impl Workspace {
             external: Some(Vec::default()),
             ignore: Some(Vec::default()),
             line_length: Some(LineLength::default()),
+            preview: Some(false),
             select: Some(defaults::PREFIXES.to_vec()),
             tab_size: Some(TabSize::default()),
             target_version: Some(PythonVersion::default()),