Dashboard and Linkage Checker to take option to resolve dependency graphs with Gradle's way

[suztomo]

Dashboard (and Linkage Checker's ClassPathBuilder) to take an option to resolve dependency graphs with Gradle's way.

While reading errors in #1982 (comment), I noticed that the dependency conflicts (due to picking up old library versions) do not occur to Gradle users.

Where is this affected?

The LtsCompatibilityTestRunner resolves the dependencies of the BOM:

    ImmutableList<Artifact> bomManagedDependencies = bom.getManagedDependencies();
    ClassPathBuilder classPathBuilder = new ClassPathBuilder();
    ClassPathResult resolvedDependencies = classPathBuilder.resolve(bomManagedDependencies, false);

This resolves the dependencies in Maven's closest-win strategy. This strategy is prone to getting old dependencies which cause dependency conflicts. For Gradle users, the resolution is different; it uses highest-win strategy. Therefore, the current result shown in the pull request contain false positives and false negatives.

GradleDependencyMediation?

We already have MavenDependencyMediation. I think the implementation would be creating GradleDependencyMediation.