Include soft keywords for is_keyword check

[dhruvmanila]

Summary

This PR updates the TokenKind::is_keyword check to include soft keywords. To account for this change, it adds a new is_non_soft_keyword method.

The usage in logical line rules were updated to use the is_non_soft_keyword method but it'll be updated to use is_keyword in a follow-up PR (#11446).

While, the parser usages were kept as is. And because of that, the snapshots for two test cases were updated in a better direction.

Test Plan

cargo insta test

[dhruvmanila]

This PR is strictly an improvement for the parser side especially the error messages. The follow-up PR #11446 updates the usages of is_keyword on the linter side which improves certain rules.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.