[AI] Add/sanitize openai input

[millerf]

Fixes @fgiannar comment

Does this pull request change what data or activity we track or use?

No

Proposed changes:

• Sanitize endpoints inputs

Testing instructions

• Deploy to your WPCOM sandbox.
• Make sure the AI blocks are still working

[github-actions]

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[github-actions]

Are you an Automattician? You can now test your Pull Request on WordPress.com. On your sandbox, run

bin/jetpack-downloader test jetpack add/sanitize-openai-input

to get started. More details: p9dueE-5Nn-p2

[jeherve]

I believe we should be able to also rely on a sanitize_callback key in our argument definition to sanitize the request's parameter. It may be worth giving it a try.

[millerf]

sanitize_callback

Thanks for such a quick feedback. Let me check...

[artpi]

I changed the description because @millerf continually edits it in a way that does not match the bot expectations.

[artpi]

Code looks good, works