Draft: implemented base gherkin feature for dms on lxd onboard
note that during implementation it became clear that python 3.12 isn't supported by pylxd when using lxd APIs. This is because some changes to ssl package introduced in python 3.12 doesn't agree with how pylxd handles websockets with wp4py package.
The issue is described in https://github.com/canonical/pylxd/issues/585
Closes #94