Add TOON support to file-based channels

[nmaguiar]

Motivation

• Provide native support for the TOON serialization format for file-backed channels so code can read/write TOON alongside existing JSON/YAML formats.
• Reuse existing af.fromTOON/af.toTOON helpers to handle TOON payloads consistently across single-file and multifile modes.

Description

• Added a new options.toon boolean to ow.ch.types.file and updated the js/owrap.ch.js docs to mention TOON support.
• Introduced a helper __fext to centralize file extension selection and used it when composing index/data filenames and delete paths.
• Implemented TOON read/write paths using af.fromTOON and af.toTOON for plain, gzip and lz4 streams in both single-file (__r, __w) and multifile (__rf, __wf) flows.
• Ensure format selection is unambiguous by disabling YAML when toon is explicitly enabled.

Testing

• Performed a syntax check with node --check js/owrap.ch.js, which completed successfully.