NEW YORK, Nov 23 (Reuters) - Retailers ranging from Walmart to Barnes & Noble are installing cameras or locking away items to deter shoplifters and thieves as they brace for a post-pandemic rush of holiday shoppers this year. Some, including Walmart, J.C. Penney, Apple Inc. and Walgreens, put in place new surveillance systems or more security guards. Others, like Target and Barnes & Noble, sealed merchandise behind plexiglass or tethered it with steel cables to store shelves. The retail industry has decried theft this holiday season as it struggles with excess inventories and a pullback in consumer spending at a...