chore(Data/Multiset): redistribute Nodup material

[Vierkantor]

Now that Multiset.Nodup lives in Multiset/Defs.lean, all the material on Nodup in Nodup.lean can be upstreamed to other files in the Multiset folder. We are left with Pairwise.forall which doesn't mention Nodup at all, so I renamed the file to Pairwise.lean. (Note that Git decided it is a deletion + addition, not a rename...)

Source of the Pairwise.lean attribution: leanprover-community/mathlib3#569

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[github-actions]

PR summary 1fca12ecaf

Import changes for modified files

Dependency changes

File	Base Count	Head Count	Change
Mathlib.Data.Multiset.Nodup	383	0	-383 (-100.00%)
Mathlib.Data.Finset.Empty	385	366	-19 (-4.94%)
Mathlib.Data.Finset.Attach	385	376	-9 (-2.34%)
Mathlib.Data.Finset.Erase	385	377	-8 (-2.08%)
Mathlib.Data.Finset.Filter	386	378	-8 (-2.07%)
Mathlib.Data.Multiset.Dedup	385	382	-3 (-0.78%)
Mathlib.Data.Multiset.Sum	400	397	-3 (-0.75%)
Mathlib.Data.Finset.Range	396	394	-2 (-0.51%)
Mathlib.Data.Multiset.Powerset	452	451	-1 (-0.22%)

Import changes for all files

Files	Import difference
There are 4205 files with changed transitive imports taking up over 183983 characters: this is too many to display!
You can run scripts/import_trans_difference.sh all locally to see the whole output.

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Declarations diff

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

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

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[Ruben-VandeVelde]

Seems reasonable

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by Ruben-VandeVelde.