Tesla said Wednesday it had agreed to invest about $2 billion in Elon Musk’s artificial intelligence startup xAI , deepening ties between the companies as the automaker pitches itself as an autonomy and robotics-driven company. Tesla’s shares were up about 2% in extended trading. Musk has framed AI technology as central to his broader push to develop artificial intelligence that could support the automaker’s self-driving and robotics ambitions. The Austin, Texas-based company reported revenue