feat: allow limiting the number of binders in delabConstWithSignature

[eric-wieser]

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This PR allows restricting the number of binders to place before the colon when using delabConstWithSignature.

This allows extract_goal in mathlib to (somewhat) respect the currently-reverted variables.

[leanprover-community-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 64b35a8c194da9f36329ee2b5d04e0e757f8c553 --onto 9a8543347796e52070ff7936661ae48fcebfea60. (2024-11-15 16:01:25)

[kmill]

I might suggest that extract_goals could wrap the target type in some metadata instead. That should block delabConstWithSignature, since it looks for exact forallE's.

[eric-wieser]

Indeed, I have an alternate patch which does just that :).