Enable `--dry-run` with `--locked` / `--frozen` for `uv sync` (#12778)
## Summary
Closes #12687.
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## Test Plan
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Added the corresponding integration tests for:
- `uv sync --dry-run --locked`
- [x] Preview lock changes
- [x] Errors if lockfile is out-of-date
- `uv sync --dry-run --frozen`
- [x] Preview lock changes
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Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>