Builds a package (.pkg) using PackageMaker.

def BuildInstallerPkg(self, output_file):
    """Builds a package (.pkg) using PackageMaker."""
    self.CreateInstallDirs()
    self.InterpolateFiles()
    self.RenameGRRPyinstallerBinaries()
    self.SignGRRPyinstallerBinaries()
    self.WriteClientConfig()
    self.Set755Permissions()
    self.RunPkgBuild()
    self.RunProductBuild()
    self.RenamePkgToTemplate(output_file)