completely refactor and modularize flake

modules/default/common/desktop/remoteBuilder.nix

@@ -0,0 +1,22 @@
+{ lib, config, ... }:
+lib.mkIf config.desktop.enable {
+	nix.buildMachines = [ {
+	  hostName = "Anton";
+    sshUser = "builder";
+	  systems = [ "x86_64-linux" "aarch64-linux" ];
+    protocol = "ssh";
+	  # if the builder supports building for multiple architectures, 
+	  # replace the previous line by, e.g.
+	  # systems = ["x86_64-linux" "aarch64-linux"];
+	  maxJobs = 1;
+	  speedFactor = 2;
+	  supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
+	  mandatoryFeatures = [ ];
+	}];
+	nix.distributedBuilds = true;
+	# optional, useful when the builder has a faster internet connection than yours
+	nix.extraOptions = ''
+	  builders-use-substitutes = true
+	'';
+  boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
+}