Extend 'Ext.menu.Item' with a simplified handler logic also used in
'PVE.button.Button'.
If 'confirmMsg' config is set we wrap the defined handler in a
confirm dialog, useful if the menu item just makes an API call and
does not has an own (edit) window shown.
In contrast to the 'pveButton' we do not have a selection model,
enable function and the respective logic here.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Acked-by: Dominik Csapak <d.csapak@proxmox.com>
