private static File relativePath(File root, String subpath) {
        return new File(root.getAbsolutePath() + File.separator + subpath);
    }
Create a ModelsEvaluator from the models found in the modelsPath. Does
not need to be in a application package.

@param modelsPath Path to a directory containing models to import
@return a ModelsEvaluator containing the imported models
config-model/src/main/java/com/yahoo/vespa/model/container/ml/ModelsEvaluatorTester.java