Python: [BREAKING] Remove FunctionTool[Any] compatibility shim for schema passthrough (#3600) (#3907)

* Fix #3600: Pass JSON schemas through without Pydantic conversion

This change optimizes FunctionTool and MCP flows by passing JSON schemas
directly to providers without converting them to Pydantic models first.

Key changes:
- Store JSON schema as-is when supplied to FunctionTool
- Skip Pydantic model_validate for schema-supplied tools in invoke()
- Return MCP tool schemas directly without conversion
- Add comprehensive tests for schema passthrough behavior

Performance benefits:
- Eliminates expensive Pydantic model creation for supplied schemas
- Preserves exact schema structure (additionalProperties, custom fields, etc.)
- Reduces memory overhead and initialization time

Maintains backward compatibility:
- Function signature inference still uses Pydantic models
- Explicit Pydantic models passed as input_model work as before
- All existing tests pass

* Fix schema passthrough validation and remove helper

* Simplify FunctionTool without generic model dependency

* Fix FunctionTool typing fallout in 3600

* Remove FunctionTool[Any] compatibility shim

* Use serializable kwargs in OTEL tool args

python/packages/github_copilot/agent_framework_github_copilot/_agent.py

@@ -499,7 +499,7 @@ class GitHubCopilotAgent(BaseAgent, Generic[OptionsT]):
 
         return copilot_tools
 
-    def _tool_to_copilot_tool(self, ai_func: FunctionTool[Any]) -> CopilotTool:
+    def _tool_to_copilot_tool(self, ai_func: FunctionTool) -> CopilotTool:
         """Convert an FunctionTool to a Copilot SDK tool."""
 
         async def handler(invocation: ToolInvocation) -> ToolResult: