support for multiconfig

You can use a single bitbake command to build multiple images or packages for different targets where each image or package requires a different configuration (multiple configuration builds). The builds, in this scenario, are sometimes referred to as “multiconfigs”, and this section uses that term throughout.

https://docs.yoctoproject.org/singleindex.html#building-images-for-multiple-targets-using-multiple-configurations

This MR adds support for multiconfig builds