DETROIT — A Detroit-area man whose decades in prison for drug dealing and work as an informant inspired the movie “White Boy Rick” filed a lawsuit Tuesday seeking $100 million, claiming he was coerced into assisting police while just a helpless teenager.Richard Wershe Jr., 52, served roughly 30 years in prison in Michigan before his release in 2017, followed by a few more years in a Florida prison for an unrelated crime.Wershe’s lawsuit in federal court in Detroit alleges that his troubles in the 1980s were related to the …