API annotate IoInterface

[navarr]

IoInterface needs to be @api annotated in order to be useful to third party developers

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• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[sidolov]

Hi @navarr , can you describe the scenario when you need to use IoInterface directly?
I think it would better to use \Magento\Framework\Filesystem\DriverInterface for scenarios with the file system, and it's already marked as API.

[navarr]

@sidolov DriverInterface is important for a class that expects an instance of \Magento\Framework\Filesystem\Io\Ftp or \Magento\Framework\Filesystem\Io\Sftp (which I would also like to see annotated and will create a PR for if this one is accepted)

[navarr]

@sidolov Is my previous description satisfactory?

[magento-engcom-team]

Hi @navarr. Thank you for your contribution.
We will aim to release these changes as part of 2.3.0.
Please check the release notes for final confirmation.