Bug 23675: Add leader and default value for ACQ

Bug 23675: Add leader and default value for ACQ

When UseACQFrameworkForBiblioRecords is set, the ACQ framework will be
use when ordering.
But the leader is not defined for this framework and then we will face
encoding issues (I haven't go far investigating this as the suggested
solution worked correctly).

The idea is to define a 000 and default to '     nam a22     7a 4500'
(which is what returns the marc21_leader.pl plugin) for ACQ.

Test plan:
0. Apply this patch and reset_all
1. Create a new basket and place a new order
2. Note that the leader is now displayed on top of the other ACQ
subfields
3. Fill in 245 with "❤️", "ö" or other UTF-8 characters you like
4. Save
5. Notice that 245$a in biblio_metadata is correctly filled with the
title you entered

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>