planet update command?

[cholmes]

One issue I've been hitting is that I need to regenerate all the planet files from the orders to get the new fields we've added. I thought I could do this pretty quickly, but have been hitting snags in merging and moving files, so was thinking about other routes to achieve this.

One would potentially be to have a command that looks for Planet data api metadata and then runs the latest convert command from that, so that it gets all the latest fields. This could be run in place, or could work like stac copy, where it updates to the latest in the copying - whichever is easiest.

Though this does seem like a fairly niche command I do think we'll likely keep evolving the Planet STAC output, so could be useful for each new iterative improvement. At some point we should make the official Planet extension and also start to version the output of this tool.