Update the NASA_DAAC_download function to write the setup credentials.

[DongchenZ]

Previously, the NASA_DAAC_download function set the credentials into the environment as default. For some users, this approach may fail to correctly set up the credentials, resulting in an HTTP 404 error when attempting to download the files. Therefore, I updated the function so the credentials will be set correctly anywhere.

The new version accepts downloading the nc files.

The user can now input multiple bands and download images given vector of band names.

Description

Motivation and Context

Review Time Estimate

• [ ] Immediately
• [ ] Within one week
• [x] When possible

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My change requires a change to the documentation.
• [ ] My name is in the list of CITATION.cff
• [ ] I agree that PEcAn Project may distribute my contribution under any or all of
  • the same license as the existing code,
  • and/or the BSD 3-clause license.
• [ ] I have updated the CHANGELOG.md.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.