added ESM-SnowMIP data

[kmdeck]

Adds the ESM-SnowMIP data - met and snow data for 10 sites, along with some site metadata.

Checklist:

• I created a new folder $artifact_name
  • I added a README.md in that that folder that
    • describes the data and processing done to it
    • lists the sources of the raw data
    • lists the required citation, licenses
  • If applicable (e.g., for Creative Commons), I added a LICENSE file [KMD: noted in README instead]
  • I added the scripts that retrieve, process, and produce the artifact
  • I added the environment used for such scripts (typically, Project.toml
    and Manifest.toml)
  • I added the OutputArtifacts.toml file containing the information
    needed for package developers to add $artifact_name to their package
• I uploaded the artifact folder to the Caltech cluster (in
  /groups/esm/ClimaArtifacts/artifacts/$artifact_name)
• I added the relevant code to the Overides.toml on the Caltech Cluster
  (in /groups/esm/ClimaArtifacts/artifacts/Overrides.toml)
• I added a link to the main README.md to point to the new artifact

[kmdeck]

@Sbozzolo I did not upload to the cluster because this is a small file (60MB). let me know if I still need to (I thought that was only for large files)

[Sbozzolo]

@Sbozzolo I did not upload to the cluster because this is a small file (60MB). let me know if I still need to (I thought that was only for large files)

I would still recommend uploading it. It is not very big, but it will save downloading 60MB every time the package has to be reinstantiated (which hopefully is not often given that use a depot)

[szy21]

Looks good to me, after addressing Gabriele's comments.