SAN FRANCISCO — In the latest clash over privacy rights in the digital age, Microsoft is suing the U.S. government over a federal law that allows authorities to examine customer e-mails or online files without the individual’s knowledge.The lawsuit comes as the tech industry is increasingly butting heads with U.S. officials over the right to view a wide range of information — including e-mails, photos and financial records — that customers are storing on smartphones and in so-called “cloud …