Update MODIS AOD converter

[weiwilliam]

Description

This PR updates the converter for the MODIS AOD product of NASA:

• Using epoch dateTime
• Adding date_range for selecting data within the time window

Issue(s) addressed

Resolves #1564

Impact

Expected impact on downstream repositories:

Checklist

• [x] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [x] I have run the unit tests before creating the PR

[BenjaminRuston]

@weiwilliam please reach out to anyone else you would like to have one last look, and otherwise will merge early next week