Engineer group should have access to db-connect permissions

Similar to rds/iam.tf

```
    {
      "Effect": "Allow",
      "Action": [
        "rds-db:connect"
      ],
      "Resource": [
        "arn:aws:rds-db:${var.region}:${var.account_id}:dbuser:${aws_db_instance.main.resource_id}/${var.project}_${var.environment}_${each.key}"
      ]
    },
    ```