provide for searching and ordering imagery in one function call

[jreiberkyle]

I find building up these bespoke request objects to be a bit cumbersome. It would be great if the python client could provide some simplified abstractions (not necessarily in this already quite large PR).

As one example, we could have an order utility that accepts an AOI and TOI, does a search, and places an order.

Originally posted by @strixcuriosus in #240 (comment)

[jreiberkyle]

Related to #645