[MM-64425] Add configurable account deletion link (#31396)

* [MM-64425] Add configurable account deletion link

* Fix types

* PR feedback

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/config.go

@@ -454,6 +454,7 @@ type ServiceSettings struct {
 	ScheduledPosts                                    *bool   `access:"site_posts"`
 	EnableWebHubChannelIteration                      *bool   `access:"write_restrictable,cloud_restrictable"` // telemetry: none
 	FrameAncestors                                    *string `access:"write_restrictable,cloud_restrictable"` // telemetry: none
+	DeleteAccountLink                                 *string `access:"site_users_and_teams,write_restrictable,cloud_restrictable"`
 }
 
 var MattermostGiphySdkKey string
@@ -989,6 +990,14 @@ func (s *ServiceSettings) SetDefaults(isUpdate bool) {
 	if s.FrameAncestors == nil {
 		s.FrameAncestors = NewPointer("")
 	}
+
+	if !isSafeLink(s.DeleteAccountLink) {
+		*s.DeleteAccountLink = ""
+	}
+
+	if s.DeleteAccountLink == nil {
+		s.DeleteAccountLink = NewPointer("")
+	}
 }
 
 type CacheSettings struct {