no-cycle rule fails to recognize external module

In a project setup with yarn workspaces, `no-cycle` fails to recognize a `@scope/package` package as external, even if the path is under `node_modules`. The reason is that `no-cycle` uses `isExternalModule`:

https://github.com/benmosher/eslint-plugin-import/blob/master/src/rules/no-cycle.js#L44

but there is a regex condition that says that module is not "external", but "scoped".

https://github.com/benmosher/eslint-plugin-import/blob/3e65a70bc73e404ace72ee858889e39732284d12/src/core/importType.js#L45

I think the right solution for consistency is to use `resolveImportType` from `importType`?

https://github.com/benmosher/eslint-plugin-import/blob/master/src/core/importType.js#L83-L93

Alternatively, replace the regular expression with "anything that does not start with a `.`.

Start with src/rules/no-cycle.js and the isExternalModule logic it uses, then compare it with resolveImportType in src/core/importType.js. Reproduce the yarn-workspace case with a scoped package under node_modules and verify that no-cycle recognizes it as external without changing other module classifications.

Written by the indexing model from the issue text.