Remove ping_tun_tap example and documentation?

A few reasons:

• example is out of date
  • doesn’t work in Python 3 without modification
  • many newer systems don’t ship with ifconfig tool
  • still using old generator-based coroutines
  • even with all issues resolved it still fails?
• requires sudo or other special permissions to run
  • not run in CI
• documentation is out of date
  • copy-pasted sources are no longer correct

[alexforencich]

Maybe we need a cocotb examples repo for stuff like this. Instead of outright removing it, move it over there where it can be worked on independent of the core cocotb codebase.

[marcinwoj]

@ktbarrett yes, it worked. However, it could have been still Python 2 (not sure that now) and also I might have changed it more, but for sure I was able to pick up/send pkts from/to tun_tap devices. Vaguely remember that I used python’s select.select() method somewhere there. I will dig up for the code and will try to update the example. It can take a few/several days though.