Bug 30646: Add welcome email support to LDAP

Bug 30646: Add welcome email support to LDAP

This patch adds the ability to enable the welcome email notice for new
users added via the LDAP replicate option.

Test plan
1) Configure LDAP for authentication
2) Enable the welcome email by adding '<welcome>1</welcome>' to your
   ldap config block
3) Confirm you have replicate enabled for your LDAP config
4) Attempt to login with an entirely new user to Koha using the LDAP
   connection (with a user who has a valid email address mapped to Koha
   borrower fields)
5) Confirm the email is sent by looking at the notices for the new user.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>