translate.wordpress.org: add cloud translation suggestions via Google Cloud Translation API

Incoming request from [Irina](https://profiles.wordpress.org/irinashl/). See [Google Cloud Translation API](https://cloud.google.com/translate)
It would need the [advanced API](https://cloud.google.com/translate/docs/advanced/translating-text-v3) to allow for glossaries but still the first 500,000 characters sent to Cloud Translation API for processing every month are free.