Add missing italian lang files in correct path

interface/web/mail/lib/lang/it.lng

interface/web/mail/lib/lang/it_mail_alias.lng

interface/web/mail/lib/lang/it_mail_alias_list.lng

interface/web/mail/lib/lang/it_mail_blacklist.lng

interface/web/mail/lib/lang/it_mail_blacklist_list.lng

interface/web/mail/lib/lang/it_mail_content_filter.lng

interface/web/mail/lib/lang/it_mail_content_filter_list.lng

interface/web/mail/lib/lang/it_mail_domain.lng

interface/web/mail/lib/lang/it_mail_domain_catchall.lng

interface/web/mail/lib/lang/it_mail_domain_catchall_list.lng

interface/web/mail/lib/lang/it_mail_domain_list.lng

interface/web/mail/lib/lang/it_mail_forward.lng

interface/web/mail/lib/lang/it_mail_forward_list.lng

interface/web/mail/lib/lang/it_mail_get.lng

interface/web/mail/lib/lang/it_mail_get_list.lng

interface/web/mail/lib/lang/it_mail_spamfilter.lng

interface/web/mail/lib/lang/it_mail_spamfilter_list.lng

interface/web/mail/lib/lang/it_mail_transport.lng

interface/web/mail/lib/lang/it_mail_transport_list.lng

interface/web/mail/lib/lang/it_mail_user.lng