It’s a freezing early December night in the heart of Bushwick, Brooklyn, and 500 Arlo Parks fans slowly shuffle into the converted garage SILO to hear… well, they don’t exactly know what. To be sure, they’re unaware that Parks’ third album, Ambiguous Desire , is finished, since the 25-year-old, two-time Grammy nominee teased these intimate gigs here and in London and New York only as an unconventional way to bring her “studio setup to the stage for a journey through old and new material” with producer, bandmate and longtime collaborator Baird. Once inside, it’s immediately clear this is no ordinary show, even for someone as comfortable opening for Harry Styles and Billie Eilish in enormodomes as she is headlining large clubs and theaters on her own.  For starters, the stage is smack in the middle of the floor, the audience is inches away from the performers, the rectangular riser loaded with gear is barely three feet off the ground and the primary light in the darkened room emanates from a bespoke box…