MM-10658 Change config fields to pointers (#9033)

* MM 10658 Change config fields to pointers (#8898)

* Change fields of config structs to pointers and set defaults

MM-10658 https://github.com/mattermost/mattermost-server/issues/8841

* Fix tests that go broken during switching config structs to pointers

MM-10658 https://github.com/mattermost/mattermost-server/issues/8841

* Apply changes of current master while switching config structs to pointers

MM-10658 https://github.com/mattermost/mattermost-server/issues/8841

* Fix new config pointer uses

* Fix app tests

* Fix mail test

* remove debugging statement

* fix TestUpdateConfig

* assign config consistently

* initialize AmazonS3Region in TestS3TestConnection

* initialize fields for TestEmailTest

* fix TestCheckMandatoryS3Fields

app/email.go

@@ -341,7 +341,7 @@ func (a *App) SendInviteEmails(team *model.Team, senderName string, senderUserId
 			}
 			bodyPage.Props["Link"] = fmt.Sprintf("%s/signup_user_complete/?d=%s&t=%s", siteURL, url.QueryEscape(data), url.QueryEscape(token.Token))
 
-			if !a.Config().EmailSettings.SendEmailNotifications {
+			if !*a.Config().EmailSettings.SendEmailNotifications {
 				mlog.Info(fmt.Sprintf("sending invitation to %v %v", invite, bodyPage.Props["Link"]))
 			}