Bug 27178: Add 'str' namespace to exclude-result-prefixes

Bug 27178: Add 'str' namespace to exclude-result-prefixes

Some nodes in the generated HTML document contain the 'str' namespace.
For instance, at the OPAC on the search result list, you can see:
<a xmlns:str="http://exslt.org/strings" href="/cgi-bin/koha/opac-detail.pl?biblionumber=18566&amp;query_desc=kw%2Cwrdl%3A%20spin" class="title">

The solution is to add 'str' to exclude-result-prefixes.
From https://developer.mozilla.org/en-US/docs/Web/XSLT/Element/stylesheet
"""
Specifies any namespace used in this document that should not be sent to the output document. The list is whitespace separated.
"""

Test plan:
0. Don't apply this patch
1. Launch a search at the OPAC
2. Inspect the title link for the records
=> Note the 'xmlns:str' attribute on tag "a"
3. Apply this patch
4. restart_all
5. Repeat 1. and 2.
=> Note that the attribute is gone now.

QA will check that no other occurrences is missing (note that one
NORMARC xsl is missing it, but NORMARC is deprecated)

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>