StaticLinkageChecker: add Gradle's dependency mediation

[suztomo]

As of now StaticLinkageChecker performs dependency mediation in the same manner as Maven does. Add an functionality to check Gradle's way, so that the result of StaticLinkageChecker makes sense to Gradle users too:

Gradle resolves version conflicts by picking the highest version of a module.

https://docs.gradle.org/current/userguide/troubleshooting_dependency_resolution.html#sub:version_conflicts

Implementation would be around StaticLinkageChecker.artifactsToClasspath