[WIP] Package runme as a snap for Linux

[dwilding]

I'm experimenting with packaging runme as a snap, for easier installation on Linux. More info about snaps

The goal is for Linux users to be able to install runme using:

snap install runme

Or possibly snap install runme --classic depending on the permissions required by runme.

Development notes

snapcraft pack  # run this in the repo root --> creates a .snap file
sudo snap install <snap_file> --classic --dangerous  # install the snap for testing