Rudder

Related to #21247, we would like to be able to avoid sync the group part or rules when importing, to accomodate to the case where we sync things between two environments.

This would work by using the Rule ID as merge identifier (ie, only do that for an imported rule for which there is already a rule with same id in current rudder).

It could also be done for directives, but there, the merge logic is more complex and the use case less needed => can be done in a second time.