feat: add translation support (#2870)

* feat: add translation support

* test(cypress): fix locale import

* docs: add locale documentation

* feat: add german translation (#2877)

* fix: locales package version, register all locales in netlify-cms

packages/netlify-cms-locales/webpack.config.js

@@ -0,0 +1,3 @@
+const { getConfig } = require('../../scripts/webpack.js');
+
+module.exports = getConfig();