Bug 30524: Core CSRF checking code

Bug 30524: Core CSRF checking code

Split out from bug 22990 as requested.

Signed-off-by: David Cook <dcook@prosentient.com.au>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit aba9e61cfbab1e915f1be4a527b5708b9ec59c35)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 6d6d36f6df79d3df22ea299934073d903f86e64a)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>