[Misc] Faster sideband position estimation

• estimate_sideband_position(), and with it from_hologram(), now searches the spectrum for the sideband with a numba kernel (CPU and GPU) instead of building masks and intermediate arrays. The sideband position found is the same as before (except for the fix for odd shapes below).

• An invalid sb argument now raises a ValueError instead of returning (0.0, 0.0).