Extend HTTPClient usage for downloads to ArtifactorySearch

[aikebah]

          Confirmed... only NexusSearch and ArtifactorySearch are pending. As both are typically solutions within the enterprise datacenter not requiring proxy access I think it would be fine to finish up this part and leave the remainder phase-out of URLConnectionFactory for a later feature-release in the 11.x series.

Originally posted by @aikebah in #6949 (comment)

Follow-up issue to #6949 to use HTTPClient for ArtifactorySearch in order to honor the standard proxy configuration also for the (expected rare) cases in which an Artifactory repository is only reachable via a proxy

[aikebah]

@irrandon, @jthurne Are you still using Artifactory with authentication?
If so, would you be able to test a snapshot version of DependencyCheck?

I'm looking for someone who can verify the correct working of ODC snapshot against an artifactory server requiring authentication by the time I've finished coding the required changes for this enhancement in order to not break its connectivity in a future ODC release.