Custom pipeline (#18079)
* Initial work
* More work
* Add tests for custom pipelines on the Hub
* Protect import
* Make the test work for TF as well
* Last PyTorch specific bit
* Add documentation
* Style
* Title in toc
* Bad names!
* Update docs/source/en/add_new_pipeline.mdx
Co-authored-by: Lysandre Debut <lysandre.debut@reseau.eseo.fr>
* Auto stash before merge of "custom_pipeline" and "origin/custom_pipeline"
* Address review comments
* Address more review comments
* Update src/transformers/pipelines/__init__.py
Co-authored-by: Lysandre Debut <lysandre.debut@reseau.eseo.fr>
Co-authored-by: Lysandre Debut <lysandre.debut@reseau.eseo.fr>
