Extract License Scanning artifact scanner

Proposal

Extract the logic used in ::Gitlab::LicenseScanning::Report so that it's used by ::Gitlab::LicenseScanning::ArtifactScanner.

Methods

The following methods will be moved as part of this proposal. This table was parsed from the following comment #378407 (comment 1192652058)

Before	After
license_scanning_report	report
expose_license_scanning_data?	has_data?
	data_available? (new method that evaluates to true if the "scanning" has been completed)