feat(RingTheory): I / I ^ 2 commutes with flat base change

[chrisflav]

Towards smooth descends along faithfully flat ring maps.

From Pi1.

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[github-actions]

PR summary 55a59319c0

Import changes for modified files

Dependency changes

File	Base Count	Head Count	Change
Mathlib.RingTheory.TensorProduct.Quotient	1192	1196	+4 (+0.34%)

Import changes for all files

Files	Import difference
Mathlib.RingTheory.LocalRing.ResidueField.Fiber Mathlib.RingTheory.LocalRing.ResidueField.Polynomial	1
Mathlib.RingTheory.TensorProduct.Quotient	4
Mathlib.RingTheory.Ideal.CotangentBaseChange (new file)	1556

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Declarations diff

+ Cotangent.lift
+ Cotangent.lift_comp_toCotangent
+ Cotangent.lift_surjective_iff
+ Cotangent.lift_toCotangent
+ cotangentToQuotientSquare_injective
+ idealMap_mul
+ tensorCotangentEquiv
+ tensorCotangentEquiv_tmul
+ tensorCotangentHom
+ tensorCotangentHom_injective_of_flat
+ tensorCotangentHom_surjective
+ tensorCotangentHom_tmul
+ tensorQuotientEquiv_symm_apply_mk_tmul
+ tensorQuotientEquiv_symm_apply_tmul
++ tensorQuotientEquiv
++ tensorQuotientEquiv_apply_tmul

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).