Implements a --flake options for build and switch, along with the usual
flake related optons (for lock-files etc).
Configurations in the flake are automatically discovered in the
following order:
1. `outputs.homeConfigurations."$flake-uri"` (the `--flake parameter`)
2. `outputs.homeConfigurations."$USERNAME@$HOSTNAME"`
3. `outputs.homeConfigurations."$USERNAME"`
Make home-manager use default configuration from
~/.config/nixpkgs/flake.nix, if it exists and nothing else is
specified.
Co-authored-by: Nicolas Berbiche <nicolas@normie.dev>
3a16ebdf72