Updating the LandTrendr.AGB.R functions

[serbinsh]

Updating the LandTrendr biomass functions to work with the new v2 dataset and write file locations to betydb

Description

Confirming functions work with v1 and v2. Other fixes. Updating file tracking to use BETYdb

Motivation and Context

Write files to BETYdb & bug fixes

Review Time Estimate

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

Types of changes

• [x] 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:

• [x] 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.

[mdietze]

@serbinsh just a reminder about this PR. Not pressing, but would be good to wrap this up