Add uuids to Director Basket - Director Basket needs to be imported twice

[Donien]

With Icinga Director 1.11.2 (no other version tested yet) I currently need to import the Director Basket twice.

After the first import (restore to database) all commands are marked with changes (when looking at the exact same snapshot of the Basket).
All changes are about Icinga Director Datafield IDs (change from "datafield_id": "(UNKNOWN)" to e.g. "datafield_id": "89").

After a second import of the exact same snapshot all is well and good, nothing is marked with changes.
However, with the second import all Datafields are duplicated while only one (of each pair) is used in a command.
This effectively clutters the Director config with unnecessary variables.

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Proposed solution

Add uuid to at least each Datafield. This way the Icinga Director knows where a certain Datafield belongs or rather if it is already present.