feat: Add rule configuration object support for tsgolint headless mode

[Copilot]

Implements support for rule configuration objects in tsgolint headless mode as requested in oxc-project/tsgolint#51.

Problem

The current tsgolint headless mode only supports passing rule names as an array:

{
  "files": [
    {
      "file_path": "/absolute/path/to/file.ts",
      "rules": ["no-floating-promises", "no-unsafe-call"]
    }
  ]
}

This prevents users from configuring rules on a per-file basis, which is essential for complex projects with varying rule requirements across different files.

Solution

Added support for rule configuration objects while maintaining full backward compatibility:

{
  "files": [
    {
      "file_path": "/absolute/path/to/file.ts",
      "rules": {
        "no-floating-promises": {
          "ignoreVoid": true,
          "ignoreIIFE": true
        },
        "no-misused-promises": {
          "checksVoidReturn": false,
          "checksConditionals": true
        }
      }
    }
  ]
}

Implementation Details

• Dual Format Support: Introduced TsGoLintRules enum supporting both Array(Vec<String>) and Object(Map<String, Value>) formats
• Custom Serialization: Implemented custom serde serialization/deserialization for seamless JSON handling
• Backward Compatibility: Uses array format by default to maintain compatibility with existing tsgolint binaries
• Environment Variable Control: Enable object format with OXLINT_TSGOLINT_OBJECT_FORMAT=1 for testing
• Infrastructure Ready: Foundation in place to extract actual rule configurations from RuleEnum instances

Testing

Added comprehensive test suite covering:

• JSON serialization and deserialization for both formats
• Backward compatibility parsing of legacy array format
• Object format with actual rule configurations
• Round-trip serialization/parsing verification

# Test current functionality (array format)
cargo test --package oxlint test_tsgolint

# Test new object format
OXLINT_TSGOLINT_OBJECT_FORMAT=1 cargo test --package oxlint test_json_serialization_formats -- --nocapture

Future Work

This implementation provides the foundation for rule configuration support. Next steps include:

1. Extract actual rule configurations from RuleEnum instances
2. Enable object format by default once tsgolint supports it
3. Add API for programmatic rule configuration

The changes are minimal and surgical, maintaining full backward compatibility while enabling the requested functionality.

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