[Core][RuntimeEnv] Add archives plugin

[weiquanlee]

Description

This PR adds an alpha archives runtime environment option for making remote, non-Python resources such as models and configuration files available to Ray tasks and actors without changing the worker's current directory or PYTHONPATH.

The new option accepts either a remote archive URI or a dictionary mapping names to URIs. Supported formats are .zip, .tar.gz, and .tgz.

This PR:

• Adds an ArchivesPlugin that downloads, unpacks, caches, and cleans up archives on each worker node.
• Exposes ray.runtime_env.get_archive_paths() for retrieving local unpacked paths from workers.
• Deduplicates repeated URIs and prevents concurrent setup from downloading the same archive more than once.
• Tracks URI references by both URI and plugin type, allowing the same URI to be used independently by working_dir and archives.
• Adds schema validation, API documentation, usage examples, and unit and integration tests.

Related issues

#65831

Additional information

Example:

from ray.runtime_env import get_archive_paths

runtime_env = {
    "archives": {
        "model": "s3://bucket/model.tar.gz",
        "config": "https://example.com/config.zip",
    }
}

archive_paths = get_archive_paths()

The returned directories are node-local shared cache directories and should be treated as read-only.

Tests run against a clean snapshot of commit 9b37c12c98:

- python -m pytest -q python/ray/tests/unit/test_runtime_env_validation.py -k archives (18 passed)
- python -m pytest -q python/ray/tests/test_runtime_env_agent.py::test_reference_table_distinguishes_uri_types (1 passed)
- python -m pytest -q python/ray/tests/test_runtime_env_archives.py (4 passed)

[gemini-code-assist]

Code Review

This pull request introduces the archives runtime environment feature in Ray, allowing remote archives to be downloaded and unpacked on worker nodes, with local paths exposed via the new get_archive_paths API. Feedback on the implementation highlights several critical issues: a potential crash in ArchivesPlugin.create when uri is None which would break all runtime environment setups; a FileNotFoundError risk in delete_uri if the local directory is missing; a NameError in the agent due to an undefined UriType annotation; and case-sensitivity in archive extension validation.

[cursor]

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