[Merged by Bors] - fix(FieldTheory/Perfect): move one/mul/pow into namespace

[wwylele]

Fixes #37936. The names one/mul/pow should obviously not in the global namespace. I also checked the rest of the file, and they look fine IMO. (e.g. powMulEquiv is only an equivalence for perfect ring so there is no ambiguity)

I did not add deprecation note because I think it makes sense for these names to go away as quick as possible and nobody should be using them.

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[github-actions]

PR summary c290b55c6e

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

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.

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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).

[wwylele]

easy

[themathqueen]

I did not add deprecation note ...

Instance names don't need deprecations, so you're good. And these definitely should not be global names: one, mul, pow.

maintainer merge

[github-actions]

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

[riccardobrasca]

Thanks!

bors merge

[mathlib-bors]

Pull request successfully merged into master.

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