Media giant Paramount Global Inc. on Monday announced it plans to merge its Paramount+ streaming service with its premium cable channel, Showtime. The integration, set to take effect later this year, essentially means Showtime subscribers on cable will get to watch Paramount+ content, such as “1923” and “Star Trek: Picard,” and streaming subscribers to the premium tier of Paramount+ will get access to Showtime titles, such as “Yellowjackets” and “Billions.” Subscribers of the lower-priced, ad-supported tier of Paramount+ will…