refactor: chat memory & chat history into core module (#1201)

examples/anthropic/chat_interactive.ts

examples/chatHistory.ts

packages/core/package.json

packages/core/src/memory/base.ts

packages/core/src/memory/chat-memory-buffer.ts

packages/core/src/memory/index.ts

packages/core/src/memory/summary-memory.ts

packages/core/src/storage/chat-store/base-chat-store.ts

packages/core/src/storage/chat-store/index.ts

packages/core/src/storage/chat-store/simple-chat-store.ts

packages/llamaindex/src/agent/base.ts

...llamaindex/src/engines/chat/CondenseQuestionChatEngine.ts

packages/llamaindex/src/engines/chat/ContextChatEngine.ts

packages/llamaindex/src/engines/chat/SimpleChatEngine.ts

packages/llamaindex/src/engines/chat/types.ts

packages/llamaindex/src/index.edge.ts

packages/llamaindex/src/memory/ChatMemoryBuffer.ts

packages/llamaindex/src/memory/types.ts

packages/llamaindex/src/storage/chatStore/SimpleChatStore.ts

packages/llamaindex/src/storage/chatStore/types.ts