Now that I have time, I've learnt that Git submodules are not supported
well with flake-based setup. Instead, I'll use my dotfiles repo as one
of the inputs as a non-flake which is exactly what I want. NICE!
While it is easier to maintain the modules by prefixing them all with
`modules`, it is not easy when used from other flakes and/or modules.
This is my attempt on making it easier with appropriate namespaces.
Update home-manager user from the restructure
