Add #required to "OpenAI API Key" field

I checked this on the 1.1.x branch of the ai module, with the ai_provider_openai version set to 1.0.2. I was able to see the client-side validation error correctly triggered when the key was left empty.
Please refer to the attached screenshot for reference.

I've Checked with above instruction and I was replicated the same error.
Please following the screenshot

Hello Everyone,
I've resolved the issue and raised an MR.
Please check and review.

Working screenshot:

Thank you!