bpo-34977: Add Windows App Store package (GH-11027)

Also adds the PC/layout script for generating layouts on Windows.
diff --git a/PC/launcher.c b/PC/launcher.c
index f3a7ddc..4c620da 100644
--- a/PC/launcher.c
+++ b/PC/launcher.c
@@ -1139,6 +1139,7 @@
     { 3320, 3351, L"3.5" },
     { 3360, 3379, L"3.6" },
     { 3390, 3399, L"3.7" },
+    { 3400, 3409, L"3.8" },
     { 0 }
 };