set Referer on loading IFrames

set Referer on loading IFrames

so tools, options, security, options,
"block any links from document not..."
applies to their contents.

Change-Id: I04839aea6b07a4a76ac147a85045939ccd9c3c79
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/150225
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Gbp-Pq: Name CVE-2023-2255.diff