Bundle brainstorm server dependencies instead of requiring npm install

Vendor node_modules into the repo so the brainstorm server works
immediately on fresh plugin installs without needing npm at runtime.

skills/brainstorming/scripts/node_modules/binary-extensions/index.d.ts

@@ -0,0 +1,14 @@
+/**
+List of binary file extensions.
+
+@example
+```
+import binaryExtensions = require('binary-extensions');
+
+console.log(binaryExtensions);
+//=> ['3ds', '3g2', …]
+```
+*/
+declare const binaryExtensions: readonly string[];
+
+export = binaryExtensions;