feat: support function call for ollama block chat api

[GeorgeCaoJ]

Summary

Ollama’s Block Chat API supports function calls when the LLM includes this feature. In agent apps, the agent with ollama LLM will use Function Call mode instead of ReAct mode to prevent unexpected function executions.

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]