fix(api): export commonjs chunks with `.cjs` extension, fix #1625 (#1627)

.changes/api-cjs-chunks.md

@@ -0,0 +1,5 @@
+---
+"api": patch
+---
+
+CommonJS chunks are now properly exported with `.cjs` extension

tooling/api/rollup.config.js

@@ -36,6 +36,7 @@ export default [
         dir: 'dist/',
         entryFileNames: '[name].cjs',
         format: 'cjs',
+        chunkFileNames: '[name]-[hash].cjs',
         exports: 'named',
         globals: {}
       },