Support NativeOutput and PromptedOutput modes in addition to ToolOutput

[DouweM]

• Fixes Structured outputs as an alternative to Tool Calling #582
• Fixes Support for returning response directly from tool #1189
• Replaces Add support for the use of response_format to force a particular json schema for the response #959

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• Wrap non-object output_type in a dict (as we do with output tools), because while OpenAI supports them, our schema generation doesn't
• Make ToolOutput and StructuredOutput not preferred but forced, erroring if model doesn't support it
• Rename StructuredOutput
• Address the many, many TODOs
• response_format=json_object for older OpenAI models?
• Manual JSON mode
• Streaming
• Other models
  • Anthropic (nothing to be done)
  • Gemini Support "responseMimeType" as part of generationConfig for Gemini #1288
• Closes Notes on structured output strategies #1615
  • Callables Support for returning response directly from tool #1189 Support functions as output_type, as well as lists of functions and other types #1785 -- to be merged first
• Properly merge JSON schemas into a union, handling $defs and $refs
• All the tests
• Documentation

[github-actions]

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[samuelcolvin]

overall looking good, but some docs and public api changes here.

[fswair]

Nice work @DouweM @dmontagu , thanks 🔥🔥

[zheller]

Awesome, thank you!!