To bolster its obesity treatment pipeline, Eli Lilly and Co. is buying Versanis Bio Inc. in a massive cash deal that could reach $1.92 billion. The total amount of the deal includes an up-front payment and development and sales milestone payments. Privately held Versanis, of Boston, brings to Lilly its lead asset bimagrumab, a monoclonal antibody that’s enjoying a resurgence since a failure in treating sarcopenia.