Bug 25793: OAI 'Set' and 'Metadata' dropdowns broken by OPAC jQuery upgrade

Bug 25793: OAI 'Set' and 'Metadata' dropdowns broken by OPAC jQuery upgrade

This patch modifies the OAI XSLT file, correcting the path to jQuery
assets and adds a link to jquery-migrate.

To test, apply the patch and make sure the "OAI-PMH" system preference
is enabled.

1. Go to: <OPACBaseURL>/cgi-bin/koha/oai.pl?verb=ListRecords&metadataPrefix=marc21
   e.g.
   localhost:8080/cgi-bin/koha/oai.pl?verb=ListRecords&metadataPrefix=marc21
2. Click on the 'Sets' and 'Metadata' links. The corresponding
   panels with set and metatdata information should be shown.

Tested against master, works as described.
Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>