The 1990s were an especially rough decade for the British royal family, a time filled with scandals about (but not exclusive to) Charles and Diana, the Prince and Princess of Wales, whose faltering marriage finally broke down for good and in public. This is where Season 5 of “The Crown” picks up, back for another rendition of All My Windsors. In the weeks leading up to the premiere, there was a good deal of foot-stamping in the media from Buckingham Palace and royal reporters concerned that Charles, just two months into his reign as king, would be portrayed harshly. The words “lurid” and “unfl…