Rewrite online translator features based on "translation-shell" process and remove obsolete Kross scripting

This merge request replaces all of the existing (and currently completely not working) scripting integrations with various online services with a re-implementation based on translation-shell. This allows to get rid of the complete Kross-based scripting integration, which currently has the only purpose to support those online translation services.

With this change, the download of translated phrases as well as download of audio files is working again. Yet, the audio file download has the current downside that only generated computer voices are working (but compared a non-working script it is a small improvement; wiktionary support is an open feature-request for translation shell).

Since the integration with translation shell is done out of process it is prone to integration errors. I want to add an additional menu with plausibility checks and user information in another MR to make this one not bigger.