add agent though config to OpenAI-API-compatible

[zxfishhack]

Summary

Add an Agent Though configuration item to the OpenAI-API-compatible model provider, corresponding to ModelFeature.AGENT_THOUGH

Close #13278

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Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[Riddhimaan-Senapati]

@zxfishhack I recommend you create an issue for this PR and link this PR to the issue as in the PR template, they can close your PR if you forget to do that. That happened to me once.