To support machine translation of paragraph, image captions, template params, reference content, the MT service should be rewritten.
* It should not be directly integrated with any particular translation unit. in CX1, we were able to translate only paragraphs. But now we can use a mixin pattern(just a suggestion) to say a translation unit is "machine translatable" and inject this new service into it
* We shoould have a way to remember the MT engine preferences and to manage default, non default mt engines for the language pair
* The content that get changed while switching between multiple clients, 'use source' should be preserved so that choosing an option from MT tool card should not result data loss at any time