Load tiny-agents from Hub

[Wauplin]

As discussed offline, this PR moves the curated collection of tiny-agents to the Hub. Agents must now be contributed to https://huggingface.co/datasets/huggingface/tiny-agents. This will be helpful to maintain the collection independently from the @huggingface/tiny-agents releases. It also makes them available for the incoming Python equivalent (huggingface/huggingface_hub#3098).

File resolution is still the same:

1. if agent_id is a file => load it as a agent.json file
2. if agent_id is a directory => load from it
3. if agent_id is a subdirectory in https://huggingface.co/datasets/huggingface/tiny-agents/tree/main => load from it
4. otherwise raise exception

Usage is still:

npx @huggingface/tiny-agents run "julien-c/flux-schnell-generator"

[julien-c]

Love it!! thanks! 🔥

[evalstate]

Really nice. I have it in mind that we should also be able to add these to the HF tool server...