filter: Add 'status' property for filter object

filter: Add 'status' property for filter object

With this property, users can control if this filter is 'on'
or 'off'. The default behavior for filter is 'on'.

For some types of filters, they may need to react to status changing,
So here, we introduced status changing callback/notifier for filter class.

We will skip the disabled ('off') filter when delivering packets in net layer.

Signed-off-by: zhanghailiang <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Yang Hongyang <[email protected]>
Signed-off-by: Jason Wang <[email protected]>