Add tool calls for openai streaming (#682)

.changeset/orange-lions-remember.md

examples/toolsStream.ts

packages/core/src/ChatHistory.ts

packages/core/src/QuestionGenerator.ts

packages/core/src/ServiceContext.ts

packages/core/src/Settings.ts

packages/core/src/llm/LLM.ts

packages/core/src/llm/fireworks.ts

packages/core/src/llm/groq.ts

packages/core/src/llm/open_ai.ts

packages/core/src/llm/together.ts

packages/core/src/llm/types.ts

packages/core/tests/CallbackManager.test.ts

packages/core/tests/Embedding.test.ts

packages/core/tests/MetadataExtractors.test.ts

packages/core/tests/Selectors.test.ts

packages/core/tests/agent/OpenAIAgent.test.ts

packages/core/tests/agent/runner/AgentRunner.test.ts

packages/core/tests/indices/SummaryIndex.test.ts

packages/core/tests/indices/VectorStoreIndex.test.ts