By DCist Contributor Mehan Jayasuriya Much like the similarly canonized Robert Johnson, Brian Wilson is an American icon for whom mythology has contributed as much to his legend of being a “musical genius” as his accomplishments have. The five years spent in a bedroom, the lost (and eventually found) masterpiece Smile, the strange, drug-induced happenings at an L.A. mansion in the 1960s and a long history of mental illness add up to something that…