static _determineAllowListMode(startPath) {
    const isNodeModule = /^.*\/(node_modules\/@.*|node_modules)\/.*$/.test(startPath);
    return isNodeModule ? 'npm' : 'git';
  }
Gets allowlist mode that determines which files to analyze
@param {PathFromSystemRoot} startPath - local filesystem path
@returns {'git'|'npm'}