feat(AlgebraicTopology/SimplicialSet/Subcomplex): add Subcomplex.unionProd, a union of products of subcomplexes

[mckoen]

Given X Y : SSet, S : X.Subcomplex, and T : Y.Subcomplex, define the subcomplex S.unionProd T : (X ⊗ Y).Subcomplex given by (X ⊗ T) ⊔ (S ⊗ Y) and provide basic API.

All code is originally written by Joël Riou and modified for PR to mathlib (with permission).

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[github-actions]

PR summary 15edd7a465

Import changes for modified files

Dependency changes

File	Base Count	Head Count	Change
Mathlib.AlgebraicTopology.SimplicialSet.Monoidal	952	964	+12 (+1.26%)

Import changes for all files

Files	Import difference
Mathlib.AlgebraicTopology.SimplicialSet.Presentable	7
Mathlib.AlgebraicTopology.Quasicategory.StrictBicategory	9
Mathlib.AlgebraicTopology.SimplicialSet.NerveAdjunction Mathlib.CategoryTheory.Category.Cat.Colimit	10
10 files Mathlib.AlgebraicTopology.SimplicialCategory.Basic Mathlib.AlgebraicTopology.SimplicialCategory.SimplicialObject Mathlib.AlgebraicTopology.SimplicialNerve Mathlib.AlgebraicTopology.SimplicialSet.FiniteProd Mathlib.AlgebraicTopology.SimplicialSet.HoFunctorMonoidal Mathlib.AlgebraicTopology.SimplicialSet.HomotopyCat Mathlib.AlgebraicTopology.SimplicialSet.KanComplex.MulStruct Mathlib.AlgebraicTopology.SimplicialSet.Monoidal Mathlib.AlgebraicTopology.SimplicialSet.ProdStdSimplex Mathlib.AlgebraicTopology.SimplicialSet.RelativeMorphism	12

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Declarations diff

+ bicartSq
+ image_β_hom
+ image_β_inv
+ isPushout
+ mem_unionProd_iff
+ preimage_image_of_isIso
+ preimage_β_hom
+ preimage_β_inv
+ prodIso
+ prod_le_prod_top
+ prod_le_top_prod
+ prod_le_unionProd
+ prod_top_le_unionProd
+ symmIso
+ top_prod_le_unionProd
+ unionProd
+ ι₁
+ ι₁_ι
+ ι₂
+ ι₂_ι

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).