feat: the think tag display of siliconflow's deepseek r1

[hjlarry]

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fix #13152

The main modifications are located between lines 240 and 252, while the remaining changes are inherited from the parent class.

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• 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

[junjiem]

@hjlarry This implementation of the code effect is not good, it is better to modify the front-end Markdown rendering part