Adding soil moisture IC function

[helge22a]

Description

The SIPNET model has the ability to run with soil moisture initial condition, so this function will download the latest vswc from EFI and create a netcdf.

Motivation and Context

Want to be able to run SIPNET with soil moisture IC.

Review Time Estimate

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

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] 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 .zenodo.json
• [ ] 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.