Basic W&B Weave integration

[shawnlewis]

• automatically initialize weave to the same project as wandb is initialized to
• just add @weave.op around your rollout function to get it traced. weave will automatically trace sub openai.chat.completions calls
• had to comment out streaming in ART's openai patch for now

[bradhilton]

Awesome, I have some changes from another branch that I'm going to have to merge in separately, but it should just work with minimal changes!