Global Squamous Cell Carcinoma of the Head and Neck Treatment Market Size, Trends, and Growth Opportunity, By Drug Class (Chemotherapy, Immunotherapy, Targeted Therapy), Type (Nasopharyngeal, Salivary Gland, Oral and Oropharyngeal, Nasal Cavity, and Paranasal Sinuses, Laryngeal, and Hypo Pharyngeal), Diagnosis (Dental Diagnosis, Imaging, Bioscopy Screening Tests, Blood Tests, Endoscopy), Treatment