Celery for jobs
## TO DO
- [x] Add Celery to the app
- [x] Job for KEGG entities creation
- [x] API route to create job and monitor it
## Docs
* https://testdriven.io/blog/fastapi-and-celery/
* https://gitlab.pasteur.fr/metagenomics/metagenedb/-/merge_requests/43
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