[Merged by Bors] - chore(Analysis/Normed/Module/WeakDual): revert polar, polar_def and isClosed_polar to weaker hypotheses

[JonBannon]

The three results mentioned inadvertently had their hypotheses strengthened in #36332. This PR recovers generality.
In addition, I have globalized variables to guard against this issue happening again and have moved part of a file that does not require NontriviallyNormedField k to Topology/Algebra/Module/WeakDual.

---

[github-actions]

PR summary 63486b57ca

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

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/pr_summary/declarations_diff.sh <optional_commit>

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

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

---

No changes to technical debt.

You can run this locally as

./scripts/reporting/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).

[themathqueen]

Pretty sure you're going to need to add those back?

[j-loreaux]

@JonBannon the shuffling in the Topology.Algebra.Module.WeakDual file is suboptimal. IThe file structure used to be like this:

• WeakDual
  • Semiring
  • Ring
• WeakSpace
  • Semiring
  • Ring

but you've changed it to:

• Semiring
  • WeakDual
  • WeakSpace
• Ring
  • WeakDual
  • WeakSpace

This is bad because it's mixing semantic content just to switch some section variables. If this file were to be split (as could potentially eventually happen), the "right" split would be into WeakSpace and WeakDual, not into Semiring and Ring, so by doing this shuffling you're hurting the organization of the file.

[themathqueen]

Thanks! Let's just have another pair of eyes on this to make sure I didn't overlook anything.

maintainer delegate?

[github-actions]

🚀 Pull request has been placed on the maintainer queue by themathqueen.

[j-loreaux]

Thanks!

bors merge

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

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