Move collection expressions from hosts/ into services/ as importable
modules
Remove service/hostname.nix collections
Remove all imports from host/ expressions and include as modules in
flake.nix
Set sensible defaults that propagate to (I think) everything
Move home-manager setup back into being NixOS module where possible
Parameterise common elements of system config to minimise rewriting and
pass as function to all places needed
Reduce complexity and in flake.nix and be more efficient in re-using
things
Removed some reduandant files in home/ and tidied up the structure
somewhat
Moved things from desktop, gui, etc... to top level
Changed env to shell, indiv shell expressions import relevant others
