[Merged by Bors] - feat(CategoryTheory): the class of morphisms given by a family of maps

[joelriou]

Given a family of morphisms f i : X i ⟶ Y i in a category C, this PR introduces that the class of morphisms ofHoms f : MorphismProperty C consisting of these morphisms f i.

---

[github-actions]

PR summary a37b197329

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff

+ Arrow.functor_ext
+ arrow_mk_comp_eqToHom
+ arrow_mk_eqToHom_comp
+ arrow_mk_mem_toSet_iff
+ homFamily
+ homFamily_apply
+ homFamily_arrow_mk
+ mk_eq_mk_iff
+ ofHoms
+ ofHoms_homFamily
+ ofHoms_iff
+ toSet

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.

---

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).

[TwoFX]

Thanks!
bors r+

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

• Build
• Lint style