Feature/grs 1955 change commonjs imports (#1995)

* GRS-1955: Using ES6 import/export in src files

* GRS-1955: Using ES6 import/export in test files

* GRS-1955: Using ES6 import/export in themes index.js

* GRS-1955: Readding blank line at end of top-languages-card.js

* feat: fix test es6 import errors

This commit makes sure jest is set-up to support es6. It also fixes
several test errors and sorts the imports.

* test: update test node version

This commit makes sure node 16 is used in the github actions.

* refactor: run prettier

Co-authored-by: rickstaa <rick.staa@outlook.com>

.github/workflows/generate-theme-doc.yml

@@ -16,7 +16,7 @@ jobs:
       - name: setup node
         uses: actions/setup-node@v1
         with:
-          node-version: "12.x"
+          node-version: "16.x"
 
       - name: npm install, generate readme
         run: |