Move systemd boot services into boot

modules/system/boot/default.nix

@@ -1,4 +0,0 @@
-{ ... }:
-{
-  imports = [ ./systemd ];
-}

modules/system/default.nix

@@ -2,7 +2,6 @@
 {
   imports = [
     ./accounts
-    ./boot
     ./devices
     ./options
     ./programs

modules/system/devices/boot/systemd/default.nix

@@ -1,5 +1,7 @@
 { ... }:
 {
+  imports = [ ./services ];
+
   boot.loader.systemd-boot = {
     enable = true;
     editor = false;