Currently when a lang test fails, (or any snapshot assertion for that
matter) the error message is rather bulky.
This is due to both sides being printed fully, using escaped newlines
(i.e. everything is one line)
This is awful to read and check what the actual difference is. Also
there is no indication that one can update the golden files using the
cli flag.
This commit changes the error message when comparing snapshots against
something
a list of lines is shown, where the output differed. An additional note
about how to update the files automatically was added too
Change-Id: Ibedcf48018c27f924b807fbd42362fb608d27441