A pretrial detainee who alleges he contracted the coronavirus and developed a case of respiratory failure in the Cook County Jail got the go-ahead to pursue his lawsuit against Sheriff Thomas J. Dart.In a written opinion this week, U.S. District Judge Matthew F. Kennelly declined to dismiss allegations that Dart in his official capacity failed to take sufficient action to protect prisoners’ health.Kennelly did not rule on the merits of Wesley Cullom’s allegations.But he held Cullom has stated a plausible claim …