VEKTIS NOVA22007: Multicenter, randomized, double-masked, 3 parallel arms, vehicle-controlled, 4-month phase III trial with a 8 month safety follow-up period to evaluate the effficacy and safety of 2 dosing regimen of NOVA22007 1mg/ml eye drops, emulsion administered 4 times a day in pediatric patients with active severe vernal keratoconjunctivitis