Bug 26127: local_referer should not compare with OPACBaseURL case insensitive

Bug 26127: local_referer should not compare with OPACBaseURL case insensitive

In our test data we have OPACBaseURL that is filled with http://kohadev.myDNSname.org:8080,
but the CGI referer in local_referer is lowercase
We should compare it without case sensitivity

Test plan:
- Use koha-testing-docker
- Notice the value of OPACBaseURL
=> http://kohadev.myDNSname.org:8080
- Use the "reports a problem" feature at the OPAC
- Notice that the "Problem found on page" is correctly filled with the
referer

Signed-off-by: Kelly McElligott <kelly@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>