Replace TC script with pyroute2 implementation

[ti-mo]

The current script for building up the hfsc/fq_codel hierarchy in lp-gw is garbage. The excellent pyroute2 library can be used to give this a proper implementation, maybe even create a stand-alone tool out of it.

• Config file per interface w/ tc tree
• Preferably atomic operations (rollbacks are supported by pyroute2-IPDB)
• systemd unit file in lp-gw to treat it as a service
• [x] Ensure feature parity with our use case in pyroute2 (fq_codel and hfsc support was missing)
• [ ] Port tc script to pure Python using pyroute2
• [ ] Write generic declarative routing toolkit and publish on PyPI
• [ ] Implement routing toolkit in ansible-lanparty

[ti-mo]

fq_codel and hfsc support was contributed to pyroute2, slowly porting tc script to Python w/ Consul support.