Add option to download assets with original filename

[matthewhanson]

Currently stactask will download assets and name the file as the <asset_key>., thereby keeping the extension, but possibly (probably) renaming the file.

Sometimes a subprocess will expect the file to be named the same as it was originally. Present as option.

[ircwaves]

@matthewhanson @philvarner @gadomski -- I'd like to motion this move from "add an option" to "make original filenames The Behavior™". But any valid argument for f"{asset_key}.{ext}" file names being preferable will easily convince me otherwise.

And yes, I've run into some external science code which depends on filenames .... again.

[matthewhanson]

This is supported by stac-asset, although don't think it's the default.
What we really need to do is drop fsspec here in favor or stac-download.

[ircwaves]

Ok, that makes sense. I'll keep a fork for immediate use, and consider #76.

[gadomski]

But any valid argument for f"{asset_key}.{ext}" file names being preferable will easily convince me otherwise.

I'm not sure which should be the default, but one benefit of f"{asset_key}.{ext}" is that you're guaranteed to not have name clashes when downloading all assets to a single directory (as long as you don't have duplicate dictionary keys). There's cases for both — IMO the "I just want to see what's there" use-case wants key-based, whereas the "I'm using this in a data pipeline" use-case wants orig-file-name.

[ircwaves]

name clashes when downloading all assets to a single directory

OK, that's the trick: asset-key (or any) file naming can run amuck if path_template doesn't separate items out by ${id}. Seems like the PR may be useful until #76 can be addressed. Incoming.