Delete/disable confirmation dialogues should check the delete requirements before asking the user for confirmation

Example scenario (based on CRM-4586 verification process):

1. User wants to delete a premium, so clicks on the delete action.
2. A confirmation page is presented, asking whether the user really wanted to delete the premium.
3. Only after the user confirms they are notified that the premium cannot be deleted, because it's linked from contribution pages.

(I assume this process might be similar in quite a few unrelated places across CiviCRM).

We should short-circuit the process by executing the 'deletability' checks earlier, and don't ask for confirmation of an action that can't possibly succeed anyway.

Bonus points for making the messages more user-friendly: for example, the message that a premium cannot be deleted should link to the premium pages that are featuring this premium, so they can be quickly visited and modified.