feat: introduce findMatchingDecl? for code quality checks wrapped in Lean.Linter (DRAFT)

[wkrozowski]

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---

This PR <short changelog summary for feat/fix, see above>.

Closes <RFC or bug issue number fixed by this PR, if any>

[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 03d7a4efd5f74dc886ba33eab424611146d49e03 --onto 16e77c407779fde9a649adf3478204d1915371a3. You can force Mathlib CI using the force-mathlib-ci label. (2026-08-21 14:14:39)

[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 03d7a4efd5f74dc886ba33eab424611146d49e03 --onto 16e77c407779fde9a649adf3478204d1915371a3. You can force reference manual CI using the force-manual-ci label. (2026-08-21 14:14:40)