The week of March 9 — when the coronavirus was officially declared a pandemic, and Tom Hanks and Rita Wilson shared the news that they had tested positive for COVID-19 — a cascade of television shows and movies shut their productions down for safety reasons. From “Stranger Things” to “The Batman,” these shutterings are temporary, and sets will be up and running as soon as it’s safe to go back into production — though no one knows when that might be.