Emily Hampshire listened to her agent when the script for horror series “Chapelwaite” arrived.“When ‘Schitt’s Creek’ was over my agent was like, ‘I want you out of those plaids and baggy jeans,’ and I think putting me in a corset was the furthest she could take that,” said Hampshire about her segue from sardonic, flannel-wearing Stevie Budd on “Creek” to Rebecca Morgan in “Chapelwaite,” set in 1850s Maine and based on Stephen King’s short story “Jerusalem’s Lot.”Premiering Sunday (Aug.