feat: add think display for volcengine and generic openapi

[xhebox]

Summary

Similar to #12949 and #13152, but for volcengine and generic openapi.

Theoritically, this could remove duplicated code in those two PRs, but sadly I don't have accounts and keys to test them... So I only add new code.

Close #13255

Tip

Close issue syntax: Fixes #<issue number> or Resolves #<issue number>, see documentation for more details.

Screenshots

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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

[crazywoola]

Does it resolve #13210 ? If so, please close the issue in the description.
Please run dev/reformat to fix the lint errors as well.

[xhebox]

Does it resolve #13210 ? If so, please close the issue in the description. Please run dev/reformat to fix the lint errors as well.

It did not solve it completely. I think #13210 also requires dify to provide deepseek-r1 automatically (in the base list).

I still add the model by myself in the setting.

[xhebox]

Does it resolve #13210 ? If so, please close the issue in the description. Please run dev/reformat to fix the lint errors as well.

Lint fixed.

[xiaoyesoso]

May I ask when the official plan is to release a new version containing this feature? Looking forward to it~