gh-113092: Add fcntl.preallocate

[aisk]

Add fcntl.preallocate as a wrapper for F_PREALLOCATE cmd on macOS.

• Issue: Missing F_* constants in fcntl module on macOS #113092

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📚 Documentation preview 📚: https://cpython-previews--139795.org.readthedocs.build/

[aisk]

Just realized that fcntl.fcntl can take an object that implements the buffer protocol as the argument, so we don't need to add a new function to do this.

Closing this PR and will make a new PR using this approach.