Update vercel ai integration for newly aligned attributes

[AbhiPrasad]

• Attribute naming:
  • Input:
    • ai.prompt.messages rename to → gen_ai.request.messages
  • Output:
    • ai.response.text rename to → gen_ai.response.text (type: string)
    • ai.response.toolCalls rename to → gen_ai.response.tool_calls (type: array ob objects)
    • Python: add gen_ai.response.finish_reasons (type: array)
  • AI client span should have list of available tools. (In Vercel now "ai.prompt.tools") Should be named "gen_ai.request.available_tools"

[github-actions]

A PR closing this issue has just been released 🚀

This issue was referenced by PR #16580, which was included in the 9.30.0 release.