The translation of sections edited by VE are saved. They need to be restored against its source sections when translation is resumed.
[x] The basic algorithm is to match against the section identifiers.
 If source article changed heavily, we need to use a better algorithm to identify source sections even if it changed.
[x] Support CX1 translations by relying on parsoid generated ids
[x] Restoring translations against source sections even if those sections moved around.
 And fallback to original source revision if source article changed beyond restoring a saved translation.
[x] Status message about fetching the saved translation should be shown to translator
 Status message about restoring the fetched translation should be shown to translator
 Restore the modified translation title if any
With the recent regressions (T187683), this ticket requires to re-evaluate the checked boxes above, and completing the remaining ones.