Bug 20422: Fix warning on uri_escape_utf8 in Output.pm

Bug 20422: Fix warning on uri_escape_utf8 in Output.pm

When opac-details calls parametrized_url, it triggers an uninitialized
warning when you would have a record without e.g. author, like:
    Use of uninitialized value in subroutine entry at /usr/share/perl5/URI/Escape.pm line 184.

This is (imo) actually a bug in URI::Escape; it should check its args.
But we resolve the warning here by adding the "// q{}" in parametrized_url.

NOTE: Along the way we do something similar in the arrParamsBusc loop.
If the variable is undefined, jump to the next one. (Consistent with the
approach in the if-part preceding it.)

Test plan:
[1] Run t/Output.t again. Should pass now.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>