Snaps as build dependencies

@joseph.wakeling your help is very welcome. As @sergiusens mentioned, the main thing to do first is buildd, which is a free software project where you can contribute too:

https://launchpad.net/launchpad-buildd

The forum post I linked earlier has information of what would be required to get snaps working in docker:

And for snapcraft itself, we have to add a new entry to the yaml, which will be very similar to build-packages but calling snap install instead of apt-get install.