API discussion for `list_collections` about astroquery

[bsipocz]

That also means to deprecate the current list_collections() method.

[andamian]

list_collections is pretty basic right now. I would use optional filtering arguments at the expense of discoverability to leave the door open for other potential orthogonal filters.

[keflavich]

I am very slightly in favor of list_collections_{sia,ssa} because of improved discoverability (tab-completion will show those). But I am also perfectly happy with the other option.

[bsipocz]

I'm even more inclined to doing the list_collections() way, as it seems that we'll get all collections combined with a simple CAOM search, so will in fact need to do more filtering to get either SIA or SSA. And who knows, maybe there will be use cases where having the combined list is useful.