Implement TODO items for ASTC encoding.
Implement TODO items for ASTC encoding.

These presets are copied over from the ARM standalone tool. I have not
tested them but they seem reasonable.

google/filament,google/filament,google/filament,google/filament,google/filament,google/filament,google/filament,google/filament,google/filament,google/filament,google/filament,google/filament