DialogView.openAndWait() provides a simpler way of working with a

dialog in an async function. It returns a promise that opens the dialog

as normal, but then waits until it's closed before resolving. With this,

it's easier to create utility dialogs without a lot of micro-management.
The resolved promise contains the dialog's closed reason, which can be

used to determine if the dialog is canceled or to access state specific

to an action or its handler.
The Error and Confirm utility dialogs now use this to simplify code

and, in the case of the Confirm dialog, to avoid resolving the promise

until the dialog is closed.

Tested this via the stories, with updates to tie the lifecycle and

results to the button states.
Tested with in-progress changes in Review Board.