Subset orders can now be submitted and the job completes. Some next steps:

* Support downloads from harmony
* Support non-subset downloads. This might be a little more complicated, as it
does not appear that the harmony API can support non-subset orders (it always
uses spatial/temporal constraints to do subsetting,  not just filtering). So we
may need to use `earthaccess` to download our granule list instead.
* Remove code supporting variable subsetting. This is not supported by Harmony,
but could be in the future.

The handling of various parameters is VERY confusing. What is necessary for CMR
vs subsetting/ordering is not clear and conifg is mutated by various parts of
the code, making it difficult to track down where values come from/get set/overridden

Makes it more clear that non-subset orders are not working right now.

There can be more than one job submitted by a user. Make it easy to track all of
the submitted jobs by initializing to a empty list and then appending to it as necessary

…subset_order`

separate concerns

Email is not an option with harmony

Separate out the subset and non-subset options