* bump zmq static dep
* lokimq -> oxenmq
* llarp_nodedb -> llarp::NodeDB
* remove all crufty api parts of NodeDB
* make NodeDB rc selection api not suck
* make path builder api not suck
* propagate all above changes so that unit tests work and it all compiles
* add conf.d directory for config overrides
* refactor llarp::Config
* add explicit constructor with datadir as parameter
* have all config files be passed as std::optional
* make Config::LoadDefault private and use std::optional in Config::Load to remove ambiguity
* update rest of codebase to reflect above changes
* fix pybind
* rename bootstrap config skipBootstrap to seednode as it's more descriptive
* make seednode configurable
* make pybind layer compile
* make pybind layer run
