Optionally disable caching of scan results for snapshot artifacts

[fviernau]

Frequently "released" snapshot artifacts can lead to large amounts of scan cache entries, this consumes storage space while it may not lead to cache hits. So it may make sense to disable storing the scan results.

Note that whether an artifact is a snapshot can sometimes be derived from the name, e.g. maven artifacts have a '-SNAPSTHOT' version extension.

[sschuberth]

Note to myself: As explained in this article, deployed snapshot artifacts as "released" to a server get the "-SNAPSHOT" suffix replaced with a timestamp. So while at one moment "1.0.0-SNAPSHOT" may resolve to "1.0.0-20220709.063105-3", a few minutes later a new snapshot might have been deployed and "1.0.0-SNAPSHOT" resolved to something else.

With that in mind I'm wondering whether we should even cache the remote artifact metadata for snapshot artifacts.