[Jobs] Add scheduled jobs api

[lhoestq]

I went with this syntax, let me know what you think:

hf jobs scheduled run hourly ubuntu echo hello world
hf jobs scheduled ps -a
hf jobs scheduled inspect <id>
hf jobs scheduled delete <id>
hf jobs scheduled suspend <id>
hf jobs scheduled resume <id>
hf jobs scheduled uv run weekly train.py

and

schedule_job(image="ubuntu", command=["echo", "hello world"], schedule="hourly")
list_scheduled_jobs()
inspect_scheduled_job(scheduled_job_id)
delete_scheduled_job(scheduled_job_id)
suspend_scheduled_job(scheduled_job_id)
resume_scheduled_job(scheduled_job_id)
schedule_uv_job("train.py", schedule="weekly")

Current limitations:

1. there is no way to pass secrets atm
   • therefore local uv script are not working (the token to download the script from the private repo on HF is missing)
2. there is no way to pass a space ID for the docker image atm

Note before merging: double check the jobSpec used as input when scheduling a job in case we rename "env" -> "environment" to align with the rest of the HTTP API

[HuggingFaceDocBuilderDev]

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