As part of the work to adapt Content Translaiton editor to translate a single section (T234323), this ticket is focused on supporting a one-section mode that allows to load the source contents displaying only one section.
The user should be able to add paragraphs to the translation as they would normally do when translating a whole article.
Since some content such as references may be defined and used on different sections, for this first approach it is ok to load the whole article and hide other sections. More advanced approaches to optimize this can be explore din T237614.
This ticket is focused on loading the section contents in a working editor. Other tickets will focus on other steps such as publishing and customizing the experience further.
