Bug 30524: [21.11] Core CSRF checking code

Bug 30524: [21.11] 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>
Bug 30524: Add xt/find-missing-csrf.t

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>
Bug 30524: (QA follow-up) Polishing xt script

Test plan:
Run it again. Same results?

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Bug 30524: Unit tests

Test plan:
Run t/Output.t
Run t/db_dependent/Auth.t

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>