General anthropic functions, steps towards experimental integration tests (#11727)

To match change in js here
https://github.com/langchain-ai/langchainjs/pull/2892

Some integration tests need a bit more work in experimental:
![Screenshot 2023-10-12 at 12 02 49
PM](https://github.com/langchain-ai/langchain/assets/9557659/262d7d22-c405-40e9-afef-669e8d585307)

Pretty sure the sqldatabase ones are an actual regression or change in
interface because it's returning a placeholder.

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/experimental/langchain_experimental/llms/anthropic_functions.py

@@ -124,11 +124,17 @@ def _destrip(tool_input: Any) -> Any:
 
 
 class AnthropicFunctions(BaseChatModel):
-    model: ChatAnthropic
+    llm: BaseChatModel
 
     @root_validator(pre=True)
     def validate_environment(cls, values: Dict) -> Dict:
-        return {"model": ChatAnthropic(**values)}
+        values["llm"] = values.get("llm") or ChatAnthropic(**values)
+        return values
+
+    @property
+    def model(self) -> BaseChatModel:
+        """For backwards compatibility."""
+        return self.llm
 
     def _generate(
         self,