[MM-40917] - Inactive Server Email Notification (#19374)

* [MM-40917] - Inactive Server Email Notification

* add email template

* make store layers

* add some store tests

* fix translations

* fix logic

* improve

* fix lint

* feedback-impl

* fix wrong text

* optimize queries

* move feature flag check

* feedback impl-1

* add line

* feedback impl

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/sqlstore/session_store.go

@@ -217,6 +217,17 @@ func (me SqlSessionStore) UpdateExpiresAt(sessionId string, time int64) error {
 	return nil
 }
 
+func (me *SqlSessionStore) GetLastSessionRowCreateAt() (int64, error) {
+	query := `SELECT CREATEAT FROM Sessions ORDER BY CREATEAT DESC LIMIT 1`
+	var createAt int64
+	err := me.GetReplicaX().Get(&createAt, query)
+	if err != nil {
+		return 0, errors.Wrapf(err, "failed to get last session creatat")
+	}
+
+	return createAt, nil
+}
+
 func (me SqlSessionStore) UpdateLastActivityAt(sessionId string, time int64) error {
 	_, err := me.GetMasterX().Exec("UPDATE Sessions SET LastActivityAt = ? WHERE Id = ?", time, sessionId)
 	if err != nil {