perf(RingTheory/LaurentSeries): add some instances

[kbuzzard]

Typeclass inference was expensively failing at some point in LaurentSeries.valuation_compare without these instances.

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Discovered by getting Claude Code to edit Lean's typeclass inference algorithm and then compile lean and mathlib and see what breaks. Found out that typeclass inference is going down a big hole in this file; this fixes the hole.

[github-actions]

PR summary 48f66c0814

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

+ instance : Field (ratfuncAdicComplPkg (K := K).space)
+ instance : Valued (ratfuncAdicComplPkg (K := K).space) (WithZero (Multiplicative ℤ))

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]

!radar

[leanprover-radar]

Benchmark results for 2c0b10f against 48f66c0 are in. No significant results found. @kbuzzard

• ✅ build//instructions: -46.7G (-0.03%)

Medium changes (1✅)

• ✅ build/module/Mathlib.RingTheory.LaurentSeries//instructions: -31.5G (-12.44%)