Becks Harvey, a 46-year-old British expat living in Brooklyn, New York, never dreamed she’d be earning six figures a year by renting out her home for photoshoots. Nor did she imagine she’d host numerous celebrities — among them, Amanda Seyfried, Jennifer Coolidge and CJ Wallace, son of The Notorious B.I.G. But like hundreds of other homeowners across the country, Harvey and her husband rent out…