Support instrumentation for messages API + models API

They are the most important for standard chatbots:<br>  [https://docs.anthropic.com/en/api/messages](https://docs.anthropic.com/en/api/messages)<br> [https://docs.anthropic.com/en/api/messages-count-tokens](https://docs.anthropic.com/en/api/messages-count-tokens)  <br> [https://docs.anthropic.com/en/api/models](https://docs.anthropic.com/en/api/models)