Bishop Ranch, the office and retail complex in San Ramon, is coming back to life. With over 30,000 employees and 600 companies in normal times, including the headquarters of Chevron and major offices for AT&T, IBM, SAP and General Electric, the sprawling East Bay office park is creating a template for work and shopping with the coronavirus as an ongoing reality. “It sets a tone,” said Alexander Mehran Jr., CEO of Sunset Development, whose family has owned Bishop Ranch for three generations. “We’re large so we can have a major impact.”