Superuser should be able to move multiple datasets in one go

[wfenrich]

Time and time again we have to move multiple datasets into a single dataverse, but currently it is possible to make it one by one. Let's change that.

We may reuse the component taken form "Assign role" modal window.

Superuser should be able to search for a dataset and select it, then to search for another etc.

[wfenrich]

If the operation fails for a given PID, we should skip it ant try with the next one. Eventually the user should be informed about the failure and the information should include the list of "failed" PIDs. It will allow user to remove obstacles and try again.

If the user selects "Force move", enforcement should be applied to all PIDs in the bulk. (For now it does NOT seem to me that we need more granular solution, i.e. separate "Force move" checkbox for each PID or something similar).