Bug 35955: Cache CSRF token in template plugin

Bug 35955: Cache CSRF token in template plugin

This change uses the Koha::Cache::Memory::Lite cache to
cache the CSRF token, so that it is only generated once,
and is re-used by the Koha::Template::Plugin::Koha object
throughout the entire template processing for the HTTP request.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 108c955eac02707ccaa35081fbece1054a5dcda3)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>