imp: pass down self to grouped folder layout

pass `self` to top level imports in the style of
`./examples/groupByConfig`

examples/groupByConfig/devshell/default.nix

@@ -1,3 +1,4 @@
+{ self, ... }:
 {
   modules = [ ./python.toml ];
 }

examples/groupByConfig/home/default.nix

@@ -1,3 +1,4 @@
+{ self, ... }:
 {
   modules = [ ./my-home.nix ];
 }

examples/groupByConfig/nixos/default.nix

@@ -1,3 +1,4 @@
+{ self, ... }:
 {
   hostDefaults.channelName = "nixos";
   hosts = {

src/mkFlake/evalArgs.nix

@@ -298,6 +298,7 @@ let
 
       nixosType = with types; submoduleWith {
         modules = [
+          { _module.args.self = self; }
           { options = (hostsOpt "nixos") // (hostDefaultsOpt "nixos") // importablesOpt; }
           legacyImportablesMod
         ];
@@ -305,6 +306,7 @@ let
 
       homeType = with types; submoduleWith {
         modules = [
+          { _module.args.self = self; }
           { options = externalModulesOpt // (exportedModulesOpt "home") // importablesOpt; }
           legacyImportablesMod
         ];
@@ -312,6 +314,7 @@ let
 
       devshellType = with types; submoduleWith {
         modules = [
+          { _module.args.self = self; }
           { options = externalModulesOpt // exportedDevshellModulesOpt; }
         ];
       };