v2.0.10-1: Debian packaging prototype

Prototype release for feedback purposes

I'm looking to move the construction of Linux packages to an sbuild-like system (we can't use sbuild directly, as it fouls around AppImages).

These artefacts are v2.0.10, but packaged with the new build environment for aarch64, armhf (NEW!), and amd64. They should otherwise be indistinguishable from the regular v2.0.10.