Make remote clients more robust #3842

Right now, at least for GOES, the client when getting the product nearest a time, is limited to the current hour. This frequently results in errors (or failed doc builds) when the hour boundary is just crossed and no products for it are yet available.

What we should do instead is match what's done in NEXRAD Level 3, which implements a recursive search, keeping track of a pair of bounds and iteratively refining them until the closest match is found.