You might not think, having endured and continuing to live through it yourself, that you could be highly entertained by a memoir of the pandemic. But you’d be mistaken. “My Little Plague Journal” by Berkeley-based author and self-styled “flaneur” L. John Harris, is an amply illustrated record of his year in isolation that is by turns quirky and erudite, inventive and purposely derivative, sometimes sobering, often satirical and occasionally downright hilarious.