Generalize scripts for building prognostic run environment

[spencerkclark]

This PR generalizes some scripts used in building the prognostic run docker image so that they can also be used in building code on Gaea or other platforms. I plan on making a followup PR with the code to actually create the environment on Gaea (this will involve updates to the fortran repo as well).

Coverage reports (updated automatically):

• test_unit: 83%

[spencerkclark]

I rebuilt and pushed the regular and GPU base images on my VM after 86e0855 (and before pushing the commit to GitHub).

[oliverwm1]

Looks good to me. Easier to read Dockerfile and useful for installing on other platforms.

Only suggested change is to parametrize the list of internal python dependencies.