don't automatically connect to not running vms/cts

don't automatically connect to not running vms/cts

this patch adds a check for the guests status, and show a start button
instead of connecting to a non-started guest

this should reduce confusion when a guest is not running, and also
reduce the number of false-positive failed console tasks

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
 [ T: re-use existing power symbol, change VM/CT to Guest ]
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>