[#14600] feat: warn on inexact deprecations

[downstream-lean4]

This is the adaptation PR for leanprover/lean4#14600.

[downstream-lean4]

Build report for Adjust mathlib

Stayed green

Repo	Critical	Build	Test	Lint
aesop	✅	✅ in 0m	✅ in 0m	⏭️
batteries	✅	✅ in 0m	✅ in 0m	✅ in 0m
import-graph	✅	✅ in 0m	✅ in 0m	⏭️
lean4-cli	✅	✅ in 0m	✅ in 0m	⏭️
mathlib4	✅	✅ in 20m	✅ in 1m	✅ in 1m
plausible	✅	✅ in 0m	✅ in 0m	⏭️
ProofWidgets4	✅	✅ in 0m	✅ in 0m	⏭️
quote4	✅	✅ in 0m	✅ in 0m	⏭️
reference-manual	✅	✅ in 1m	⏭️	⏭️
BibtexQuery		✅ in 0m	⏭️	⏭️
comparator		✅ in 0m	⏭️	⏭️
cslib		✅ in 1m	✅ in 0m	✅ in 0m
doc-gen4		✅ in 0m	⏭️	⏭️
illuminate		✅ in 0m	✅ in 0m	⏭️
lean4-unicode-basic		✅ in 0m	✅ in 0m	⏭️
lean4export		✅ in 0m	✅ in 0m	⏭️
LeanSearchClient		✅ in 0m	✅ in 0m	⏭️
leansqlite		✅ in 0m	✅ in 0m	⏭️
repl		✅ in 0m	✅ in 0m	⏭️
verso		✅ in 2m	✅ in 1m	⏭️
verso-slides		✅ in 1m	✅ in 0m	⏭️
verso-web-components		✅ in 0m	⏭️	⏭️

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