feat: e-mail templates (#1158)

* View definition added

* Get templates and texts from the database.

* Fill in texts in templates

* Fill in texts in templates

* Client API added

* Weekly backup

* Weekly backup

* Daily backup

* Weekly backup

* Tests added

* Corrections from merge branch

* Fixes from pull request review

internal/org/repository/eventsourcing/model/mail_template.go

@@ -0,0 +1,31 @@
+package model
+
+import (
+	es_models "github.com/caos/zitadel/internal/eventstore/models"
+	iam_es_model "github.com/caos/zitadel/internal/iam/repository/eventsourcing/model"
+)
+
+func (o *Org) appendAddMailTemplateEvent(event *es_models.Event) error {
+	o.MailTemplate = new(iam_es_model.MailTemplate)
+	err := o.MailTemplate.SetDataLabel(event)
+	if err != nil {
+		return err
+	}
+	o.MailTemplate.ObjectRoot.CreationDate = event.CreationDate
+	return nil
+}
+
+func (o *Org) appendChangeMailTemplateEvent(event *es_models.Event) error {
+	mailTemplate := &iam_es_model.MailTemplate{}
+	err := mailTemplate.SetDataLabel(event)
+	if err != nil {
+		return err
+	}
+	mailTemplate.ObjectRoot.ChangeDate = event.CreationDate
+	o.MailTemplate = mailTemplate
+	return nil
+}
+
+func (o *Org) appendRemoveMailTemplateEvent(event *es_models.Event) {
+	o.MailTemplate = nil
+}