Added action types and updated reducer for the "process holders" action.
- Holders are marked as PENDING_ESTABLISHMENT or PENDING_REMOVAL, before making Blob calls
- Afterwards they're either removed or marked as ESTABLISHED.
- In case of failure, all of them are marked as NOT_ESTABLISHED / NOT_REMOVED. This will be then handled by a handler component (introduced later) for retrying.
Depends on D13403