Serialize the uci list value into a space separated string before passing
it to String.format() for HTML escaping. Without that change, empty strings
were returned whenever the underlying uci get operation yieled an array.
Fixes: #4993
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
(cherry picked from commit 5c792aefc744d1417fc9e24cfb92cd61cf8a651f)
06dd6b521d