Replace cJSON with another JSON library

### Description

Problems with cJSON:

1. Undermaintained
2. "Lots" of allocations (how big of an issue is this? not sure)
3. Will leak memory depending on which cJSON APIs you use

Alternatives:

1. [yyjson](https://github.com/ibireme/yyjson)
2. [jansson](https://github.com/akheron/jansson)
3. Wrap a C++ JSON library to create a C library

cc @alexttx 