When fetching stubs / contracts in a CI, shared environment, what might happen is that
both the producer and the consumer reuse the same local Maven repository. Due to this,
the framework, responsible for downloading a stub JAR from remote location,
can't decide which JAR should be picked, local or remote one. That caused
the `"The artifact was found in the local repository but you have explicitly
stated that it should be downloaded from a remote one"` exception
and failed the build.
For such cases we're introducing the property mechanism:
- via `stubrunner.snapshot-check.skip` system property
- via `STUBRUNNER_SNAPSHOT_CHECK_SKIP` environment variable
if either of these values is set to `true`, then the stub downloader will not
verify the origin of the downloaded JAR.
fixes gh-545
d87e669a23