Acorn spack-stack v2 updates

[AlexanderRichert-NOAA]

Description

This PR:

• updates the site config for Acorn for spack-stack v2/spack v1 -- it only supports oneAPI 2024.2.1
• adds an experimental deploy.py script for YAML-configured push-button installations on Acorn
• updates fetch_cargo_deps.py to first try to use a given spec's associated rust installation, as well as add cargo_home/bin/ to PATH when running cargo because apparently at least some versions need that in order to find rustc.

Dependencies

none

Issues addressed

Related to #1772
Related to #1604

Applications affected

UFS WM, GW, misc. EMC

Systems affected

Acorn

Testing

• Additional testing:
  • deploy.py tested on Acorn

Checklist

• This PR addresses one issue/problem/enhancement or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.
• All necessary updates to the documentation on readthedocs are included in this PR
  • For site config updates, check in particular doc/source/PreConfiguredSites.rst and doc/source/MaintainersSection.rst
• All necessary updates to the spack-stack wiki will be made when this PR is merged

[climbfuji]

I'll wait for the CI tests to pass, thanks for the chained env bug fixes.

[AlexanderRichert-NOAA]

A couple final tweaks. Any future updates will be a separate PR.

[Hang-Lei-NOAA]

It takes a long time to read the copilot review. But its concerns are all about the impact on other platforms, after a carefully reading. Copilot is trying to optimize it to a universal frame not considering the specific settings for acorn.
I am going to try it on Acorn.