Rewrite emailer based off DB triggers

[DougLau]

Server emails are fragile and agency specific. Replace them with DB client using NOTIFY/LISTEN. This should be added to honeybee, using the lettre crate.

Affected system attributes:

• email_rate_limit_hours
• email_recipient_action_plan
• email_recipient_dmsxml_reinit
• email_recipient_gate_arm
• email_sender_server
• email_smtp_host
• action_plan_alert_list

[DougLau]

For v5.64, the Java email support has been replaced with an email_event table in the DB that logs email alerts.