Bug 28912: Prevent Pseudonymization to be set if bcrypt_settings not set

Bug 28912: Prevent Pseudonymization to be set if bcrypt_settings not set

If Pseudonymization is set but the bcrypt_settings config used by the
feature is not set, then there is an ugly 500 on checking out.

bad bcrypt settings at /kohadevbox/koha/Koha/PseudonymizedTransaction.pm line 116.

However it's pretty hard to handle correctly this exception (and that's
why it hasn't be done initially). However we could prevent the pref to
be turned on if the config entry is not present.

Test plan:
Remove the bcrypt_settings from the config
Try to turn the syspref on
Add the config
Try to turn the syspref on/off

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
JD amended patch: fix qa failures

Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>