[BottomSheet] Remove private header imports from MaterialBottomSheet.h
[BottomSheet] Remove private header imports from MaterialBottomSheet.h

PiperOrigin-RevId: 301909458

material-components/material-components-ios,material-components/material-components-ios,material-components/material-components-ios,material-components/material-components-ios,material-components/material-components-ios