Additional functionality desired for query_config

#1388 is improving query_config, partly to address #1190 . However, many aspects of https://github.com/ESMCI/cime/issues/1190#issuecomment-282928761 are not addressed in that PR.

I see the most important outstanding requests as:

1. For each compset, a listing of which grids are scientifically and test-supported for that compset

1. Allow subsetting compsets by the first letter of the compset, rather than cam/clm/etc., along with some help text saying "B means XXX, F means YYY", etc. This is important because it's not necessarily intuitive that you get I compsets by specifying `--compsets clm`.