function legacyPackageCheck(legacyDirectory) {
    return fs.existsSync(legacyDirectory) && !fs.existsSync(path.join(legacyDirectory, "package.json"));
}
A "legacy package" is an extension that was installed based on the GitHub name without
a package.json file. Checking for the presence of these legacy extensions will help
users upgrade if the extension developer puts a different name in package.json than
the name of the GitHub project.

@param {string} legacyDirectory directory to check for old-style extension.