- Get rid of CryptoManager.
- Get rid of Crypto.
- Move all the Crypto instance methods to llarp::crypto functions.
(None of them needed to be methods at all, so this is simple).
- Move sodium/ntru initialization into static initialization.
- Add llarp::csrng, which is an available llarp::CSRNG instance which is
a bit easier than needing to construct a `CSRNG rng{};` in various
places.
- Various related small simplifications/cleanups.
* 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