Mannitol Recruiting Phase 1 / 2 Trials for Recurrent Adult Brain Neoplasm / Medulloepithelioma / Ototoxicity / Atypical Teratoid/Rhabdoid Tumor / Central Nervous System Embryonal Tumor / Recurrent Childhood Medulloblastoma / Childhood Ependymoblastoma / Childhood Atypical Teratoid/Rhabdoid Tumor / Adult Supratentorial Primitive Neuroectodermal Tumor / Adult Central Nervous System Germ Cell Tumor / Adult Medulloblastoma / Adult Embryonal Tumor With Multilayered Rosettes, C19MC-Altered / Adult Ependymoblastoma / Recurrent Childhood Supratentorial Primitive Neuroectodermal Tumor / Adult Supratentorial Embryonal Tumor, Not Otherwise Specified / Recurrent Childhood Central Nervous System Embryonal Neoplasm / Recurrent Childhood Pineoblastoma / Germ Cell Tumors / Recurrent Childhood Malignant Germ Cell Tumor / Adult Pineoblastoma / Childhood Central Nervous System Germ Cell Tumor / Childhood Embryonal Tumor With Multilayered Rosettes, C19MC-Altered / Recurrent Childhood Supratentorial Embryonal Tumor, Not Otherwise Specified Treatment