Bug 35305: Add XSLT for authority details page in staff interface

Bug 35305: Add XSLT for authority details page in staff interface

This adds a new system preference 'AuthorityXSLTDetailsDisplay'.
If set, authority MARCXML will be transformed using the XSLT
at the given filename or URL.
The HTML output will be displayed in place of tabs in details page.

The syspref value can contain {langcode} and {authtypecode} which will
be replaced by the appropriate value (resp. current language and
authority type code).

Test plan:
1) Apply patch and run updatedatabase
2) Search for an authority type GEOGR_NAME and view details page
3) Verify that display is not affected yet
4) Create an XSLT file (for example in /home/koha/xslt/en/GEOGR_NAME.xsl)
5) Set 'AuthorityXSLTDetailsDisplay' system preference to :
   /home/koha/xslt/{langcode}/{authtypecode}.xsl
6) Refresh details page
7) Verify that display matches what you expect from the XSLT
8) Set 'AuthorityXSLTDetailsDisplay' system preference to :
   <path to sources>/koha-tmpl/intranet-tmpl/prog/en/xslt/UNIMARCauthDetails.xsl
8) Refresh details page
9) Verify that display matches what you expect from your XSLT

Example of a minimal XSLT:

<?xml version='1.0' encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
 xmlns:marc="http://www.loc.gov/MARC21/slim"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output omit-xml-declaration="yes"/>
  <xsl:template match="marc:record">
    <xsl:element name="div">
      <xsl:attribute name="class">
        <xsl:text>authority-summary</xsl:text>
      </xsl:attribute>
      <xsl:value-of select="marc:datafield[@tag='151']/marc:subfield[@code='a']"/>
    </xsl:element>
  </xsl:template>
</xsl:stylesheet>

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>