feat(Bicategory/Oplax): Fix simp lemmas and renaming

[callesonne]

This PR renames OplaxNatTrans to OplaxTrans and puts it in the Oplax namespace (as the should be oplax natural transformations also between lax functors).

It also removes @[simp] from OplaxTrans.id and OplaxTrans.vcomp, and instead adds @[simp!] to the CategoryStruct instance. This is needed as for example, right now, in order to prove that (η ≫ θ).app a = η.app a ≫ θ.app a simp needs to first convert this to (OplaxTrans.vcomp η θ).app a which is not ideal (in particular it converts (η ≫ θ) to OplaxTrans.vcomp η θ).

This is part of some of the restructuring that I want to do before constructing the bicategory of pseudofunctors.

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• [ ] depends on: #18250

[github-actions[bot]]

PR summary a852ff77cd

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

+ OplaxTrans + OplaxTrans.StrongCore + StrongOplaxTrans + _root_.CategoryTheory.OplaxNatTrans + instance : Inhabited (OplaxTrans F F) + instance : Inhabited (StrongOplaxTrans F F) - OplaxNatTrans - StrongCore - instance : Inhabited (OplaxNatTrans F F) - instance : Inhabited (StrongOplaxNatTrans F F) -+-+ id --++ vcomp

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).

[mathlib4-dependent-issues-bot]

This PR/issue depends on:

• ~~leanprover-community/mathlib4#18250~~ By Dependent Issues (🤖). Happy coding!

[Ruben-VandeVelde]

It seems like deprecated aliases for the renamed declarations are missing?

[callesonne]

Okay I am back to fixing some of these old PRs again, sorry about this! I have added deprecation tags now.

[github-actions[bot]]

🚀 Pull request has been placed on the maintainer queue by YaelDillies.

[mathlib-bors[bot]]

Pull request successfully merged into master.

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