Be explicit with mypy ignores

[carmocca]

What does this PR do?

Be explicit with mypy and ignore exactly the failing files.

This has the advantage that any new files will need to be typed. Also, we no longer need to maintain 2 lists, which was prone to errors.

Does your PR introduce any breaking changes? If yes, please list them.

None

Before submitting

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• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• [n/a] Did you make sure to update the documentation with your changes? (if necessary)
• [n/a] Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• [n/a] Did you list all the breaking changes introduced by this pull request?
• [n/a] Did you update the CHANGELOG? (not for typos, docs, test updates, or internal minor changes/refactorings)

PR review

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cc @carmocca @akihironitta @Borda

[github-actions]

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[akihironitta]

99 PRs away... 😅