Non-Destructive Testing (NDT) Market Size, Share & COVID-19 Impact Analysis, By Offering (Equipment and Service (Inspection Service, Training Service, Calibration Service, and Equipment Rental Service), By Method (Visual Inspection, Surface Inspection, Volumetric Inspection, and Others), By Technique (Ultrasonic Testing, Visual Inspection Testing, Magnetic Particle Testing, Liquid Penetrant Testing, Eddy-Current Testing, Radiographic Testing, Acoustic Emission Testing, and Others), By Vertical (Manufacturing, Oil & Gas, Aerospace, Public Infrastructure, Automotive, Power Generation, and Others