feat(Data/Finset/Prod): add Equiv.Finset.prod

[b-mehta]

The choice of simp lemmas and simps setup is chosen here to match Equiv.Set.prod, for consistency.

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[github-actions]

PR summary 4cd4643e0d

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ _root_.Equiv.Finset.prod

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

## summary with just the declaration names:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

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No changes to strong technical debt.

No changes to weak technical debt.

[wwylele]

The choice of simp lemmas and simps setup is chosen here to match Equiv.Set.prod, for consistency.

Did you forget to add @[simp(s)]?

[b-mehta]

Nope, precisely because Equiv.Set.prod doesn't either!