Rework model operation command

[baumannsven]

1. If creating with the button render the paste model button.
   To create this button, you should use the internal method build command when creating it.
   This will also execute the corresponding event get operation button.

2. Extract drag model button from the template and build this with the button render too.

This has to be done so that we can freeze the data definition later. To still be able to control the user permission in.

dc-general/src/Contao/View/Contao2BackendView/ButtonRenderer.php

Line 275 in 7efbf06

private function buildCommand($command, $model, $previous, $next, $isCircularReference, $childIds)