added SMTP monitor (#5489)

Co-authored-by: Frank Elsinga <frank@elsinga.de>

db/knex_migrations/2025-01-01-0000-add-smtp.js

@@ -0,0 +1,12 @@
+exports.up = function (knex) {
+    return knex.schema
+        .alterTable("monitor", function (table) {
+            table.string("smtp_security").defaultTo(null);
+        });
+};
+
+exports.down = function (knex) {
+    return knex.schema.alterTable("monitor", function (table) {
+        table.dropColumn("smtp_security");
+    });
+};