Add token usage information

[vishwamartur]

Related to #50

Add token usage information to the response from the LLM.

• aisuite/framework/chat_completion_response.py

  • Add attributes for token usage information to the ChatCompletionResponse class.
  • Update the __init__ method to initialize token usage attributes.

• aisuite/providers/anthropic_provider.py

  • Update the normalize_response method to include token usage data.

• aisuite/providers/aws_provider.py

  • Update the normalize_response method to include token usage data.

• aisuite/providers/azure_provider.py

  • Update the chat_completions_create method to handle token information.
  • Add normalize_response method to include token usage data.

• aisuite/providers/fireworks_provider.py

  • Update the _normalize_response method to include token usage data.

• aisuite/providers/google_provider.py

  • Update the normalize_response method to include token usage data.

• aisuite/providers/huggingface_provider.py

  • Update the _normalize_response method to include token usage data.

• aisuite/providers/ollama_provider.py

  • Update the _normalize_response method to include token usage data.

• aisuite/providers/together_provider.py

  • Update the _normalize_response method to include token usage data.

[rohitprasad15]

Thanks for this PR. Can you re-visit and check your solution after the addition of pydantic checks in the codebase.
Please tag me for any questions or for review once you are done.