Extend mock capabilities to cover / simulate BPF filtering & socket options

[fako1024]

Currently mock interfaces / sockets do not cover the classical socket options, such as snaplen, BPF filters or promiscuity. Maybe not all, but some of these features should / could be added to mock interfaces to improve the realism.

DoD

• Assess options
• Implement BPF filtering
• Implement snaplen handling (on socket level if possible)
• Implement promiscuity (probably not possible / irrelevant)