- remove profiles::postfix::gateway wrapper class entirely
- move all postfix configurations to hieradata/roles/infra/mail/gateway.yaml
- add deep merge lookup options for postfix::configs, postfix::maps, and postfix::virtuals
- use hiera_include to include postfix module directly
- add voxpupuli-postfix module to Puppetfile
- create profiles::postfix::gateway class with config based on efa5
- add master.cf entries for postscreen, smtpd, dnsblog, and tlsproxy services
- create postfix hash files: aliases, access controls, canonical maps
- configure TLS with system PKI certificates and strong cipher suites
- add transport and virtual alias mappings for mail routing
Reviewed-on: #414