Replace microbundle with rollup

Author: XhmikosR

.babelrc.js

@@ -0,0 +1,3 @@
+# https://github.com/browserslist/browserslist#readme
+
+defaults

.browserslistrc

@@ -68,6 +68,18 @@ module.exports = {
         sourceType: 'module',
       },
     },
+    {
+      files: [
+        'rollup.config.mjs',
+      ],
+      env: {
+        node: true,
+        browser: false,
+      },
+      parserOptions: {
+        sourceType: 'module',
+      },
+    },
     {
       files: [
         'site/**',