feat: add deprecated_module

[wkrozowski]

This PR adds deprecated_module command.

[wkrozowski]

!bench

[leanprover-radar]

Benchmark results for aaf53b1 against 8f6ade0 are in. There are no significant changes. @wkrozowski

• 🟥 build//instructions: +3.0G (+0.02%)

Small changes (4🟥)

• 🟥 build/module/Lean.Elab.BuiltinCommand//instructions: +274.0M (+1.66%) (reduced significance based on *//lines)
• 🟥 build/module/Lean.Elab.Import//instructions: +84.1M (+5.05%) (reduced significance based on *//lines)
• 🟥 build/module/Lean.Parser.Command//instructions: +156.7M (+1.30%)
• 🟥 compiled/workspaceSymbolsNewRanges//instructions: +4.7M (+0.63%)

[mathlib-lean-pr-testing]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 8f6ade06ea2964d55625a9809f3349a0112aee04 --onto 87180a09c49c91577e54284703c73c5ca76be126. You can force Mathlib CI using the force-mathlib-ci label. (2026-03-20 10:42:43)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 8f6ade06ea2964d55625a9809f3349a0112aee04 --onto cfa8c5a036d6990635c6ec50b02d0e806995cec3. You can force reference manual CI using the force-manual-ci label. (2026-03-20 10:42:44)