Make the feedback link language-variable for release

This involves setting some i18n messages for the target languages based on the
translations already provided - I hope this doesn't break anything for TWN but
the need for this only just became apparent; apologies!

Longer-term we will need to come up with a better way of doing this, if we are
keeping the in-VisualEditor feedback link around.

Change-Id: Id6ed80cdcd4314e84e75fb718421767162d73ef3
Merge "Make the feedback link language-variable for release"