Load/store config to json for Star chips
This is a reworking of the json loading code from the star branch. This time, I've not copied code directly from the branch, as I went a different way. I hope the result is understandable.
There's a default_star.json file, but also see the examples in tests/star/test_json.cpp.
Currently, it's missing the fuse ID and serial number, which will need a separate branch (I tried not to change StarChips in this branch).