Johnson Controls Inc. and Tyco International PLC agreed to merge in a $14 billion deal that creates a new giant provider of commercial-building systems and reflects a growing push by some executives and shareholders toward companies that are bigger but more focused. The deal, announced Monday, would combine Johnson Controls’ business selling heating and air-conditioning equipment for skyscrapers, schools, hospitals and other structures with Tyco’s lines of security and fire-suppression gear into a company with more than $30 billion a year in sales.