with-reasonml: better setup (#4218)

With this setup we're compiling the .re/.ml files directly to source
directories with a .bs.js extension, and enabling next.js to pick up
that extension for pages.

examples/with-reasonml/.gitignore

 bs
 .merlin
 lib/
+*.bs.js

examples/with-reasonml/bsconfig.json

@@ -3,7 +3,11 @@
   "sources": ["components", "pages"],
   "bs-dependencies": ["reason-react", "bs-next"],
   "reason": { "react-jsx": 2 },
-  "package-specs": ["commonjs"],
+  "package-specs": {
+    "module": "commonjs",
+    "in-source": true
+  },
+  "suffix": ".bs.js",
   "bsc-flags": [
     "-bs-super-errors"
   ],

examples/with-reasonml/next.config.js

+module.exports = {
+  pageExtensions: ['jsx', 'js', 'bs.js']
+}

examples/with-reasonml/package.json

@@ -2,9 +2,9 @@
   "name": "with-reasonml",
   "version": "1.0.0",
   "scripts": {
-    "dev": "bsb -clean-world -make-world && next dev lib/js",
-    "build": "bsb -clean-world -make-world && next build lib/js",
-    "start": "next start lib/js"
+    "dev": "concurrently \"bsb -clean-world -make-world -w\" \"next dev\"",
+    "build": "bsb -clean-world -make-world && next build",
+    "start": "next start"
   },
   "license": "ISC",
   "dependencies": {