[magics] Allow model parameters to be specified

[dlqqq]

Problem

Allow users to specify model parameters (e.g. temperature) when invoking a model through the %%ai magic command.

Proposed Solution

Not sure. My initial guess is that:

1. Common OpenAI-API-compatible parameters available to most LiteLLM models like temperature and top_k should be available as command-line flags.

2. Additional arguments may be passed as a dictionary, e.g. --args={...}.