[feature] When ingesting VEX documents add NoVuln node if package is not affected

[dejanb]

Is your feature request related to a problem? Please describe.
During development of VEX CSAF support we ignored packages described as not affected by the vulnerability. It was left to be handled in separate issue.

Describe the solution you'd like
If package is not affected, add NoVuln node.

[lumjjb]

@dejanb I think i recall this conversation being about products that did not have a vulnerability. Is that accurate? or am i recalling wrong?

[dejanb]

@lumjjb I think that's tracked with #1016. This one is to specifically track adding `NoVuln' nodes where appropriate
https://github.com/guacsec/guac/pull/729/files#r1245467401

I might as well recalling it wrong, so please feel free to add more issues/context to this.