feat(CategoryTheory/Limits): sigmaConst preserves colimits

[joelriou]

More precisely sigmaConst.obj R commutes with colimits. We also compute the cokernel of (sigmaConst.obj R).map f when f is a map in Type*.

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[github-actions]

PR summary 528ee405fb

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
5 files Mathlib.Algebra.Category.ModuleCat.Sheaf.Free Mathlib.Algebra.Category.ModuleCat.Sheaf.Generators Mathlib.Algebra.Category.ModuleCat.Sheaf.PullbackFree Mathlib.Algebra.Category.ModuleCat.Sheaf.Quasicoherent Mathlib.AlgebraicGeometry.Modules.Tilde	1
Mathlib.CategoryTheory.Limits.Preserves.SigmaConst (new file)	466

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Declarations diff

+ freeFunctor_map
+ freeFunctor_obj
+ instance :
+ instance [HasCoproducts.{w} C] (R : C) :
+ instance [HasCoproducts.{w} C] {α β : Type w} (f : α → β) :
+ isColimitSigmaConstCokernelCofork
+ sigmaConstCokernelCofork
+ ι_sigmaConstCokernelCofork_π
+ ι_sigmaConstCokernelCofork_π_eq_zero

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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Increase in tech debt: (relative, absolute) = (2.00, 0.00)

Current number	Change	Type
6799	2	backward.isDefEq.respectTransparency

Current commit fe922455ff
Reference commit 528ee405fb

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).