Manually set product & desktop name

The goal here is to ensure that the desktop shortcuts and user-visible
values remain friendly (HTTP Toolkit) but all binaries and config files
are kept short & consistent (httptoolkit).

package.json

@@ -27,7 +27,8 @@
     "extends": null,
     "productName": "HTTP Toolkit",
     "extraMetadata": {
-      "name": "httptoolkit"
+      "name": "httptoolkit",
+      "productName": "httptoolkit"
     },
     "files": [
       "**/*",