Preserve the order of bard and replicator sets

[lazerg]

Reordering the sets on a Bard or Replicator field doesn't stick when blueprints are stored with the eloquent driver on MySQL. MySQL sorts the keys of a JSON object when it stores it, so the sets come back out in a different order to the one they went in with.

The blueprint repository already works around this for tabs and sections by keeping a __count on each of them. This does the same for the set groups and sets nested in a field's config, and strips it back out when the blueprint is read or exported. The import command gets it too, since it writes to the database without going through the repository.

Fieldsets have the same problem and aren't covered here, as FieldsetRepository does no order handling at all and would need its own pass. Happy to follow up with that if you want it.

Fixes statamic/cms#15152.

[ryanmitchell]

I've applied it to fieldsets too for completeness. thanks for your work on this.