Single API function brings in nlohmann json as dependency

[roland-sipos]

We bring in JSON as a dependency for this single API for configuring the generators:

tpglibs/src/TPGenerator.cpp

Line 14 in 0b221a9

TPGenerator::configure(const std::vector<std::pair<std::string, nlohmann::json>>& configs,

Maps should be sufficient and would remove this dependency.