GH-49751: [Python] Add raw fd support to pa.OSFile

[alippai]

Rationale for this change

The goal of the MR is to support the low level python raw fds (os.open())

What changes are in this PR?

As an alternative to the str path, the pa.OSFile accepts the int parameter as well.

Are these changes tested?

Yes, new end-to-end tests were added

Are there any user-facing changes?

Yes, the API is extended with a new parameter type

This MR was created by Codex Cloud.

• GitHub Issue: Support raw fds in pyarrow OSFile #49751

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

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Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

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See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[github-actions]

⚠️ GitHub issue #49751 has been automatically assigned in GitHub to PR creator.