### Check existing issues - [x] I've verified that this request isn't described by any existing issues. ### Request We, builders of a kernel snap for UC, would like to be able to use the modprobe.d configuration we have in our source deb file in the generated snap. In order to do that, we use the kernel-module-load interface, thus plugs, but there is currently no solution to build that except manually synchronizing the plugs and the modprobe.d configuration used for our classic ubuntu images. Current solution for that would be a specific script to run before snapcraft that would fetch the .deb, parse its content and append the right yaml to snapcraft.yaml. This is tedious, complicated and error-prone. If a command like `craftctl add-plug`, `craftctl set-plug` or similar was available, we could use it to implement this from snapcraft.yaml itself, making the system easier and safer to use. ### The problem it solves <!-- Describe the impact your request would have. --> Being able to automate this would make our maintenance work much easier, prevent issues from appearing or remainding on UC while being fixed on classic ubuntu. source: https://chat.canonical.com/canonical/pl/4dfd6hzbcbbyzjmw6krydzsedw