Stabilize DB search output

[wagoodman]

With DB v6 there will be substantial changes made to the DB structure. We'd like to have a way for users to have a common interface with stable output (not directly tied to the DB schema/shapes) across grype versions.

The search command should be expanded to:

• Query a single CVE to get the NVD record (always one)
• Query a single vulnerability ID to get the vulnerability record(s)

Are there more use cases we should capture?

This output should be available in:

• table output
• json output

All json output should have a JSON schema describing valid/expected shapes/values.

[TimBrown1611]

please notice to this kind of issue in grype db search - #2085
(can be solved in the same task)