If there’s any hope of loving a heroine harboring a past that includes ramming a scissor into the chest of her teenage tormentor, you’d better hope she’s played by an actress as transfixing as Jessie Buckley. But she’s hardly the only reason to experience the intoxicating depravity of Michael Pearce’s thrilling Gothic romance “Beast.” There’s also the smoldering sexuality of her hunky hunk of burning love co-star Johnny Flynn.