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/authentication.go

@@ -138,7 +138,7 @@ func (a *App) CheckUserPreflightAuthenticationCriteria(user *model.User, mfaToke
 }
 
 func (a *App) CheckUserPostflightAuthenticationCriteria(user *model.User) *model.AppError {
-	if !user.EmailVerified && a.Config().EmailSettings.RequireEmailVerification {
+	if !user.EmailVerified && *a.Config().EmailSettings.RequireEmailVerification {
 		return model.NewAppError("Login", "api.user.login.not_verified.app_error", nil, "user_id="+user.Id, http.StatusUnauthorized)
 	}