feat(CategoryTheory/Cat/Basic): API for converting between 2-morphisms in Cat and natural transformations.

[edegeltje]

This PR adds definitions as NatTrans.toCatHom2 and NatTrans.toCatIso2 (mirroring Functor.toCatHom), and adds simp lemmas for normalizing these to operations on functors and natural transformations (rather than bicategorical operations).

This paves the way to a possible future where these aren't equal (for avoiding defeq abuse).

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[github-actions]

PR summary 5db554c938

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

+ _root_.CategoryTheory.Cat.associator_toCatHom_hom
+ _root_.CategoryTheory.Cat.associator_toCatHom_inv
+ _root_.CategoryTheory.Cat.id_of
+ _root_.CategoryTheory.Cat.id_toCatHom
+ _root_.CategoryTheory.Cat.leftUnitor_toCatHom_hom
+ _root_.CategoryTheory.Cat.leftUnitor_toCatHom_inv
+ _root_.CategoryTheory.Cat.rightUnitor_toCatHom_hom
+ _root_.CategoryTheory.Cat.rightUnitor_toCatHom_inv
+ _root_.CategoryTheory.Cat.toCatHom_whiskerLeft_toCatHom₂
+ _root_.CategoryTheory.Cat.toCatHom₂_whiskerRight_toCatHom
+ ofCatHom₂
+ ofCatIso₂
+ of_toCatHom₂
+ of_toCatIso₂
+ toCatHom_comp_toCatHom
+ toCatHom_congr
+ toCatHom_id
+ toCatHom₂
+ toCatHom₂_associator_hom
+ toCatHom₂_associator_inv
+ toCatHom₂_comp_toCatHom₂
+ toCatHom₂_congr
+ toCatHom₂_id
+ toCatIso₂
+ to_ofCatIso

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 script/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).