Add warning in case of missing sandbox permissions

[FrancescoCaracciolo]

• Add a warning dialogue with the message to run to give the necessary permissions
• If the users tries to toggle off command virtualization while the permissions aren't available, the warning appears
• Added a method requires_sandbox_escape to each handler that returns if sandbox escape is required for each handler
• If there are not enough permissions and requires_sandbox_escape is True, then a warning is shown near the handler and the user can't select it
• Fixed espeak makes settings crash if the there are not enough permissions