lib/monorepo.js
function getGroupForPackageFile (groups, packageFilePath) {
  return Object.keys(groups).find((group) => {
    return groups[group].packages && groups[group].packages.includes(packageFilePath)
  })
}
function getGroupForPackageFile (groups, packageFilePath) {
  return Object.keys(groups).find((group) => {
    return groups[group].packages && groups[group].packages.includes(packageFilePath)
  })
}
Given a groups array and a package path, returns the package file’s group, or undefined