Use case-preserving packageName_ROOT env variables in auto-generated modules

[climbfuji]

Description

Use case-preserving packageName_ROOT env variables in auto-generated modules instead of all uppercase PACKAGENAME_ROOT.

See JCSDA/spack-stack#1068 for a list of systems that need to get updated for spack-stack-1.7.0.

Issue(s) addressed

Resolves JCSDA/spack-stack#1066

Related spack develop issue: spack#43569

Dependencies

n/a

Impact

Fixes cmake warnings and build errors.

Checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have run the unit tests before creating the PR

[climbfuji]

@AlexanderRichert-NOAA I am going to plow ahead here. I just discussed with the spack developers and we'll look into a more general solution for spack after their next release that will allow users to state if they want lowercase, case-preserving (which for the case of spack packages is the same as lowercase), and uppercase. We'll get this update in from spack mainline once it is ready, but for now we can revert to what we had beforehand. Please follow spack#43569 for updates on spack develop.

[AlexanderRichert-NOAA]

Yep sounds good to me, I agree it's not worth the pain right now :)