On her new album, “West End Girl,” released with a week’s notice on Friday, Allen takes a new tack. It’s a lurid, linear and detail-filled account of the dissolution of a marriage — widely believed to be a tell-all about Allen’s failed union with the “Stranger Things” actor David Harbour, an assumption spurred on by Allen in interviews (with the caveat, she told The Times of London, “I don’t think I could say it’s all true”). “West End Girl” finds Allen writing candidly about discovering a partner’s affair, her desire to find refuge in alcohol and prescription drugs, and her struggles to enter into an open relationship. In essence, Allen has become the tabloid, airing out the last remains of her own dirty laundry before anyone else can.