A Phase 2, Randomized, Open-Label Three-Arm Clinical Study To Evaluate The Safety And Efficacy Of Lenvatinib (E7080/MK-7902) In Combination With Pembrolizumab (MK-3475) Versus Standard Of Care Chemotherapy And Lenvatinib Monotherapy In Participants With Recurrent/Metastatic Head And Neck Squamous Cell Carcinoma (R/M HNSCC) That Have Progressed After Platinum Therapy And Immunotherapy (PD-1/PD-L1 Inhibitors) (LEAP-009)