The Beau Biden Foundation for the Protection of Children raked in $3.9 million in 2020, but spent only a fraction of that on its purported mission to help kids, The Post has learned. The Delaware-based charity, which was started in honor of President Biden’s late son, got an infusion of $1.8 million from the Biden Foundation before that group shut down in 2020, according to the charities’ latest tax filings. The Biden Foundation was started by Joe Biden and his wife, Jill Biden, to champion “progress and prosperity for American families.” The Beau Biden charity also took in $225,000 from...