More defaults & heuristics to help orders?

[cholmes]

When I was making the quickstart in #472 I was struck how many options I needed to supply to create an order:

$ planet orders create --name my-first-order --id <scene-ids> --item-type PSScene --bundle visual

It seems like many of those we could have reasonable defaults or heuristics for. Like could we get all the way to:

$ planet orders create --id <scene-ids>

I feel like Explorer manages to figure out the item-type from the id, so hopefully we could have some way to just figure it out too. That to me is one that would help - I often have to look up the item-type to make sure I have it right.

We could also try to give a default name to the order, perhaps like a date-stamp and user name or something? I often struggle to come up with some name to use. And we could also come up with some default bundles, perhaps by item-type.

With #366 this should all just go in the request creation.