We currently have the ability to migrate the integrations from all customers into Kessel / SpiceDB at once. We want to do that for a restricted list of internal orgs at first, for testing purposes.

The migration is done in KesselAssetsMigrationService and triggered from an internal REST API call. The endpoints from that class need a new parameter (could be a POST request body) which will be used to pass a collection of org IDs. If that parameter is missing or empty, the endpoints should migrate the integrations from all orgs into Kessel. Otherwise, the endpoints should only migrate the integrations from the provided orgs.

Acceptance criteria:

• POST /kessel/migrate-assets accepts a collection of org IDs (string).
• POST /kessel/migrate-assets/async accepts a collection of org IDs (string).
• If any of the two endpoints receives a collection of org IDs that is not missing or empty, it should only migrate the integrations from the provided orgs into Kessel. Otherwise, it should migrate integrations from all orgs into Kessel.
• The unit tests are updated to include the new restriction.