feat(cli): add collection output formats

[tunglambk]

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Description

Fixes #2319.

Make eodag list print only collection identifiers by default, one per line. Add mutually exclusive --json and --yaml options for full collection metadata; the YAML option keeps the former human-readable metadata layout without its introductory header.

Tests: uv run --extra dev pytest -q tests/test_cli.py (37 passed); uv run --extra dev prek run --files eodag/cli.py tests/test_cli.py docs/cli_user_guide.rst.

Further comments

None.