Bundling additional recipe repositories

[vvolkl]

Feature request: would be neat if during the build one could specify (by github link) additional package repos beside builtin to be included.

[haampie]

Hey, yeah, this could be useful. Feel free to fork this github repo and change the github action to do just that, it shouldn't be terribly hard.

For instance add a line after this: https://github.com/haampie/spack-batteries-included/blob/master/.github/workflows/update.sh#L36