Add spinner to Generate Shipping Label button

[AjinkyaM1]

Current behavior

Currently, when we click on the Generate Shipping Label button while fulfilling a transfer order, the button remains enabled. Since generating the label takes some time to display to the user, they can click the button again, resulting in multiple API calls to the carrier. This can sometimes causes issue in the backend.

Expected behavior

A spinner should be added to the button when generating a label for a transfer order. This will indicate to the user that the label generation is in progress.