v2 API, o1 models metadata, and support typos in model names

[sgoedecke]

• Use the updated models metadata API, which changes the shape of the models object
  • As a result of this, we've got to collect some extra data from the index endpoint response before fetching schema/details. No big deal, since it's already in-memory
• Include the basic metadata about o1 models in the list
• Make more resilient to typoed or missing model names by telling the model to just pick the closest one (e.g. so "Phi 3 mini" becomes "Phi-3-mini-128k-instruct")
• Fixes an issue where we were passing params that were unsupported for some models, so executeModel was failing for models like Mistral-Nemo

[itsbagpack]

One suggestion to ensure that version is a string and not a number