Allow async/await in Confirmation Service

[joemaylor]

I'm using the ConfirmationDialog component, and I think the default experience with asynchronous accept callbacks could be improved.

Currently, the accept callback is not able to be asynchronous. That is, as soon as the accept callback is run, the dialog closes. I am not able to await the API call.

async function deleteRow(data: IRow) {
  await fetch(...)
}

function onDelete(data: IRow) {
  confirm.require({
    header: 'Delete?',
    message: `Are you sure you want to delete ${data}?`,
    rejectLabel: 'Cancel',
    acceptLabel: 'Delete',
    acceptProps: {
      outlined: true,
      severity: 'error',
    },
    position: 'right',
    accept: async () => await deleteMyRow(data),
  })
}

Currently this results in the following experience:

1. I press confirm on the confirmation dialog.
2. The dialog closes.
3. Some time passes...
4. The API call resolves.

Ideally:

1. I press confirm on the confirmation dialog.
2. The API call resolves (await the accept callback).
   i. Maybe during this time, the dialog cannot be closed, the 'cancel' button is disabled, and the 'accept' button is loading?
3. The dialog closes.

Here is a crude implementation of these changes. If there is some positive feedback here, and this feature could be implemented, I'd be happy to expand this to cover other similar components, e.g. ConfirmationPopup: joemaylor/primevue@7ccfe52