Pyrophosphate Prompted Aggregation-Induced Emission: Chemosensor Studies, Cell Imaging, Cytotoxicity, and Hydrolysis of the Phosphoester Bond with Alkaline Phosphatase: Pyrophosphate Prompted Aggregation-Induced Emission: Chemosensor Studies, Cell Imaging, Cytotoxicity, and Hydrolysis of the Phosphoester Bond with Alk