Tracking Issue for `--print=crate-root-lint-levels`

This is a tracking issue for the MCP 833 "Add --print=crate-root-lint-levels to retrieve lints levels" (https://github.com/rust-lang/compiler-team/issues/833).
The flag is gated under -Zunstable-options.

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.

A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

Discussion comments will get marked as off-topic or deleted.
Repeated discussions on the tracking issue may lead to the tracking issue getting locked.

Steps

• Implement the MCP (https://github.com/rust-lang/rust/pull/139184)
• Adjust documentation (see instructions on rustc-dev-guide)
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

• Should renamed lints be included?
• Should removed lints be included?

Implementation history

• https://github.com/rust-lang/rust/pull/139184

Start with the tracking issue, implementation PR #139184, and the rustc-dev-guide documentation and stabilization guides. Review the two unresolved questions about renamed and removed lints, then determine the documentation and stabilization work needed to complete the unchecked checklist items.