Bug 18754: Translatability: Get rid of exposed tt directives in opac-detail.tt

Bug 18754: Translatability: Get rid of exposed tt directives in opac-detail.tt

The file opac-detail.tt exposes a lot of template directives to translation where translators should not be confronted with.

Some examples from po file are:

$[% SUBFIELD.code %] [% SUBFIELD.value %]

%s [%% INCLUDE \"openlibrary-readapi.inc\" bib = { normalized_isbn => "
"normalized_isbn, lccn => lccn, normalized_oclc => normalized_oclc } %%]

See: [% IF ( nextTitle ) %][% nextTitle |html %][% ELSE %]next biblio[% END "
"%]

To test:
- Apply patch
- Do a search in OPAC that has more than 1 results
- Go to the detail page of one of the items found
- Verify that the details display as before and that you can
  browse the results with Previous and Next
- In staff client, change OPACXSLTDetailsDisplay from 'default' to
  empty for "no xslt" and repeat steps above
- In staff client, set HTML5MediaEnabled to 'OPAC' or 'OPAC and staff client'
- Verify that media catalogued in field 856 still work
- Create a new translation for a 'language' aa-AA (perl translate create aa-AA)
- Verify that template directives ar no longer exposed in aa-AA-opac-bootstrap.po

Followed test plan which works as intended

Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 752aef4593f1aa2d64700bf9738e7e03907eb1cd)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>