[FEATURE]: Add KEV information to vulnerablity

## Describe the feature

The schema should be expanded so that the `Vulnerability` type can include information if the vulnerability has been included on a KEV (Known Exploited Vulnerability) list as provided by CISA or ENISA.

## Possible solutions

Should contain the following properties:

* KEV Provider
* Date of retrieval
* Boolean flag for inclusion on list
* Date when vulnerability was added to the list

## Alternatives

None

## Additional context

Has already been discussed here: https://github.com/CycloneDX/specification/issues/481#issuecomment-2166313328