(WIP) adding Julia coding env

[wukaixingxp]

This PR is adding Julia coding env. The env is based on this branch but improved in the following way:

1. allow system env to be passed in to the docker env, like PORT, NUM_WORKER to change the env as needed by other training framework, like TorchForge. (This change will apply to all envs)
2. Added memory_gb, request_timeout_s and timeout_sto control the docker and requests. (This change will apply to all envs)
3. Make Julia coding env as efficient as possible by creating long-running Julia process pool.
   This PR can run with TorchForge and happy to discuss if there is a better way on how we can allow user to config the env.

[github-actions]

✅ Deployment succeeded for julia_env

• Space repo: https://huggingface.co/spaces/openenv-testing/julia_env-pr-170
• Live URL: https://openenv-testing-julia-env-pr-170.hf.space

Nice work! Wait for a code review and we're ready to go.

You can iterate locally or validate fixes by running scripts/deploy_to_hf.sh --env "julia_env".

[github-actions]

✅ Deployment succeeded for julia_env

• Space repo: https://huggingface.co/spaces/openenv-testing/julia_env-pr-170
• Live URL: https://openenv-testing-julia-env-pr-170.hf.space

Nice work! Wait for a code review and we're ready to go.

You can iterate locally or validate fixes by running scripts/deploy_to_hf.sh --env "julia_env".