Bug 14769: Put ControlledIndicators to work

Bug 14769: Put ControlledIndicators to work

This patch does:
[1] Adds Koha::Authority->controlled_indicators (with a test).
[2] Adds a call to controlled_indicators in AuthoritiesMarc::merge.
    Unit test Merge.t is extended too.
[3] Simplifies the code in authorities/blinddetail-biblio-search.pl by
    calling controlled_indicators.

Test plan:
[1] Run t/db_dependent/Koha/Authorities.t
[2] Run t/db_dependent/Authority/Merge.t
[3] Steps 3 to 7 for MARC21:
    Create a PERSO_NAME authority with 008/11=r and ind1=3
[4] Edit a biblio and add a 600 linked to the new authority.
[5] Verify that the biblio has ind1==3 and ind2==7 and $2==aat.
    (If $2 is not visible, check the metadata in biblio_metadata.)
[6] Edit the PERSO_NAME authority and change 008/11 to '|' (bar).
[7] Verify that merge updated your biblio record: $ind2==4 and $2 gone.
[8] UNIMARC: Follow the pattern from steps 3 to 7.
    Create authority, link it in a biblio, check indicators (they should
    be copied both). Edit authority, change indicators and verify the
    merge results in the biblio record.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Tested PERSO_NAME and UNIF_TITLE.
For UNIF_TITLE the second authority indicator is copied to ind1 or ind2,
depending on the biblio tag involved.
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>