Bug 33957: Add normalized_oclc and only fetch when needed

Bug 33957: Add normalized_oclc and only fetch when needed

opac-user.tt wants to normalized_oclc number if using syndetics or B&T images

We don't need to fetch it if not, but we need to pass it if so

To test:
1 - Switch all Syndetics prefs to 'Show' or 'Use' except
    SyndeticsClientCode = just enter 'test'
2 - Checkout some items to a patron, ensure the records have:
    - ISBN
    - UPC
    - OCLC number
3 - View opac-user.pl (sign in to opac as the user)
4 - View the network console tab (may need to reload)
5 - Note requests like:
    https://secure.syndetics.com/index.aspx?isbn=1780335792/MC.GIF&client=test&type=xw10&upc=&oclc=
6 - Note that oclc parameter is not filled for record with an oclc number
7 - Apply patch
8 - Reload
9 - Confirm the link now has oclc as expected
10 - Disable syndetics, enable google books or another source
11 - Confirm images display as expected

JD amended patch: tidy

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>