Bug 14303: Fix item search CSV export - obsolete "by" and display of publication...

Bug 14303: Fix item search CSV export - obsolete "by" and display of publication year for MARC21

The exported CSV file from the item search didn't display the publication
year in MARC21 installations and the title always contained 'by'
even if there was no author information to display. Also the by is
not needed by MARC21 as the data should include punctuation.

This basically copies the changes done to the JSON format
on bug 13859 to the CSV include.

To test: Switch from 'Screen' to 'CSV'
- Check publication date always displays (MARC21 and UNIMARC)
- Check that for MARC21 the 'by' has been removed from the title information
- Check that for UNIMARC the 'by' only displays when there is also
  an author to display

Tested for MARC21, works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>