Allow listing only top level packages in the package list modification

[Managor]

It would be nice if the firmware package selector allowed me to list only the packages that are not a dependency of any other package. This would allow me to disregard dependency level package changes like what happened with the move from libustream-wolfssl to libustream-mbedtls. I would assume it would also cut down on the "Error Building Firmware Image" reports that I see on this issues page.