Trends in Gas-Phase Fluoride Ion Affinities of Main-Group Oxyfluorides and Fluoride Sulfides. Generation and Characterization of the Fluoride Adducts of FAsO, FPO, FPO2, F2SiO, F4SO, FBO, F2SiS, FPS, FAsS, F2S2, and S2O by Ion Cyclotr