An “Antifa” street thug can now look forward to continuing his fight — from jail. David Campbell, 32, copped a plea for his role in a 2018 beatdown outside the Night for Freedom party in Manhattan organized by right-wing activist Mike Cernovich. Campbell pleaded guilty to two counts of felony assault and will be sentenced on Oct. 23 to 18 months in the slammer, reps for Manhattan District Attorney Cy Vance Jr. told The Post. ... “When the Proud Boys [a far right fraternal organization] got into a street fight with Antifa members, it was a nationwide story. The Mayor...