Migrate to NVD 2.0 API

[oswalpalash]

Description

As noted from #224 , we need to upgrade to the NVD 2.0 API. There is a significant redesign in the way the API works, but our stuff should mostly keep working. Tested it locally and it seemed to not make major mistakes. cc @joshbressers please test it because I know you might have more insights on this from the v1 API work.

Fixes #224

Type of change

Changes NVD Data Source from v1 of their API to v2.

Please delete options that are not relevant.

• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• [x] Tested locally against the copy of gsd-database.

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules

[joshbressers]

Apologies for how long this took. I truly appreciate the code!