Say hello to GitLab Duo Chat: A new level of AI-assisted productivity

Introduces GitLab Duo Chat, a new AI-powered conversational interface for developers. It provides in-context assistance for code explanations, test generation, code creation, issue summarization, and learning GitLab features. It leverages Anthropic Claude-2 and Vertex AI Codey LLMs, emphasizing data privacy by not using user code for training. Chat will be integrated into the Web IDE and VS Code extension.