Query MAST with new instrument/mode values due to change in MAST definitions

[bhilbert4]

Replacement for #29
Resolves #28

MAST has recently been updated such that the values the in "instrument" column are no longer e.g. "MIRI" but instead include information on the mode as well (e.g. "MIRI/IMAGE"). Because of this, when querying for only e.g. "MIRI", the results included only files which have not yet been reprocessed in MAST to use the new format. This PR works around this change by making a query using the Observations class in the MAST API. This initial query (which can use a wildcard for its search e.g. "MIRI*") returns a list of the instrument/mode values in the data of interest. This instrument/mode list is then placed into the original query to the Jwst.Filtered database, in order to get back filenames.

This PR replaces #29 just because git after the merge of #30, I tried to rebase the branch for #29 but git continued acting as if all of the changes from #30 were new. This made it hard to see the real changes in #29. So I started again with a new branch off of main (which include the updates for #30). So now the only changes listed in here are those directly related to the MAST updates (along with a bunch of spaces that are removed, thanks to sublime text).

[bhilbert4]

I tested this fix using the command below, and am now seeing data acquired after Feb 28 (which is when the MAST update started automatically working on new data). In the results I see files with both MIRI and MIRI/IMAGE instrument values.

python jwst_download.py -v --propID 2311 --config jwst_query.cfg --lookbacktime 13 --instrument miri --filetypes uncal