[Merged by Bors] - chore(SetTheory/Cardinality/Cofinality/Club): use namespace

[vihdzp]

I meant to do this in #37677, but forgot to do git push.

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[github-actions]

PR summary 111f394ed8

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_.Order.IsNormal.isClub_fixedPoints
+ _root_.Order.IsNormal.isClub_range
+ csSup_mem
+ iInter
+ iInter_of_cof_le_one
+ iInter_of_orderTop
+ inter
+ isLUB_mem
+ of_isEmpty
+ sInter
+ sInter_of_cof_le_one
+ sInter_of_orderTop
+ union
+ univ
- IsClub.csSup_mem
- IsClub.iInter
- IsClub.iInter_of_cof_le_one
- IsClub.iInter_of_orderTop
- IsClub.inter
- IsClub.isLUB_mem
- IsClub.of_isEmpty
- IsClub.sInter
- IsClub.sInter_of_cof_le_one
- IsClub.sInter_of_orderTop
- IsClub.union
- IsClub.univ
- Order.IsNormal.isClub_fixedPoints
- Order.IsNormal.isClub_range

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.

[kbuzzard]

Thanks for taking the trouble to tidy up!

bors merge

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

• ci (staging) / Post-CI job
• ci (staging) / Build
• ci (staging) / Lint style
• ci (staging) / Post-Build Step