Bergamot-based machine translation

### Describe the problem

There are Bergamot models that are used for offline translations in Firefox. It might not be as accurate as commercial models but might provide good enough results for some situations without sacrificing privacy.

### Describe the solution you would like

Add machinery backend using one of the libraries. It would be internal without calling external services.

### Describe alternatives you have considered

_No response_

### Screenshots

_No response_

### Additional context

* https://github.com/XapaJIaMnu/translateLocally
* https://browser.mt/
* https://github.com/browsermt/bergamot-translator
* https://github.com/jerinphilip/slimt/
* https://pypi.org/project/kotki/
* https://github.com/mozilla/firefox-translations-models/