coral-web: support langchain multihop

[wujessica]

Description:

This PR adds support for rendering tool events sent from the langchain multihop chat endpoint, including adding the functionality to render images from the python interpreter in multihop mode.

Tests:

To test, add USE_EXPERIMENTAL_LANGCHAIN=true to your .env file. Then, select the python_interpreter and internet search tools and ask a query like plot the 3 tallest mountains in the world.

https://github.com/cohere-ai/cohere-toolkit/assets/5898755/bb1b0c5e-0734-4f9c-afe6-cb4f56110e46