Kde: move kwin configs and patches into separate file

roles/kde/programs/kwin.nix

@@ -0,0 +1,45 @@
+{...}: {
+  nixpkgs.overlays = [
+    (
+      final: prev: {
+        kdePackages = prev.kdePackages.overrideScope (
+          kFinal: kPrev: {
+            kwin = kPrev.kwin.overrideAttrs {
+              patches =
+                kPrev.kwin.patches
+                ++ [
+                  ./patches/kwin-pr6406.patch
+                ];
+            };
+          }
+        );
+      }
+    )
+  ];
+  home-manager.users.toast = {
+    programs.plasma = {
+      kwin = {
+        titlebarButtons = {
+          left = ["on-all-desktops" "keep-above-windows"];
+          right = ["minimize" "maximize" "close"];
+        };
+        virtualDesktops = {
+          rows = 1;
+          number = 2;
+        };
+      };
+      configFile = {
+        "kwinrc" = {
+          "org.kde.kdecoration2"."BorderSize".value = "None";
+          "TabBox"."LayoutName".value = "thumbnail_grid";
+        };
+      };
+      shortcuts = {
+        "kwin" = {
+          "Switch One Desktop to the Left" = ["Meta+Ctrl+Left"];
+          "Switch One Desktop to the Right" = ["Meta+Ctrl+Right"];
+        };
+      };
+    };
+  };
+}