feat(MulAction): add a SMulDistribClass instance for subgroups

[xroblot]

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[github-actions]

PR summary 2b9cd2f090

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

+ smulDistribClass

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 scripts/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).

[xroblot]

!bench

[leanprover-radar]

Benchmark results for fc4b136 against 2b9cd2f are in! @xroblot

• 🟥 build//instructions: +7.0G (+0.00%)

No significant changes detected.

[xroblot]

!bench

[leanprover-radar]

Benchmark results for 50a6a6c against 2b9cd2f are in! @xroblot

• 🟥 build//instructions: +13.2G (+0.01%)

Small changes (1🟥)

• 🟥 build/module/Mathlib.Util.ParseCommand//instructions: +128.5M (+5.16%) (reduced significance based on absolute threshold)