`trim_messages` and `ChatAnthropic` token counter with tools

### Privileged issue - [x] I am a LangChain maintainer, or was asked directly by a LangChain maintainer to create an issue here. ### Issue Content `ChatAnthropic.get_num_tokens_from_messages` uses Anthropic's [token counting API](https://docs.anthropic.com/en/api/messages-count-tokens) and will error for invalid message sequences. These constraints are not respected inside `trim_messages`. See below for examples. ```python from functools import partial from langchain_anthropic import ChatAnthropic from langchain_core.messages import AIMessage, HumanMessage, ToolMessage from langchain_core.messages.utils import trim_messages from langchain_core.tools import tool @tool def get_weather(location: str): """Get the weather.""" pass tools = [get_weather] llm = ChatAnthropic(model="claude-3-5-sonnet-latest").bind_tools(tools) messages = [ HumanMessage("hi"), AIMessage("hello"), HumanMessage("what's the weather in florida?"), AIMessage( [ {"type": "text", "text": "let's check the weahter in florida"}, { "type": "tool_use", "id": "abc123", "name": "get_weather", "input": {"location": "florida"}, }, ], tool_calls=[ { "name": "get_weather", "args": {"location": "florida"}, "id": "abc123", "type": "tool_call", }, ], ), ToolMessage( "It's sunny.", name="get_weather", tool_call_id="abc123", ), ] ``` ## Example 1 ```python trim_messages( messages, max_tokens=200, token_counter=llm, ) ``` Breaks when we attempt to count tokens in a reversed list of messages: https://github.com/langchain-ai/langchain/blob/db8201d4dafb533133cc51c87c7ef011e546e03f/libs/core/langchain_core/messages/utils.py#L1309-L1312 > BadRequestError: Error code: 400 - {'type': 'error', 'error': {'type': 'invalid_request_error', '…