HMGB1 and Schwartz-Jampel syndrome: Semi‐quantitative analysis of high mobility group box 1 (HMGB1) immunohistochemistry (IHC) staining in healthy, maculopapular exanthema (MPE) and Stevens–Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) skin biopsy sections from the Cleveland Clinic archival cohort