resolve size_t issues

[lucasxia01]

We use size_t in way too many places. We should probably just use uint32_t or uint64_t by default and cast to size_t when needed. This leads to Mac build serialization issues as Charlie brought up in Slack, but it also led to issues in using msgpack for wasm as it didn't match size_t with any serializable type.

[codygunton]

There are good reasons for the suggested change. IIRC We run into issues because this function returns a size_t https://en.cppreference.com/w/cpp/container/vector/size and we'd have to have a lot of casting and/or change compiler error rules.

[ledwards2225]

Incremental improvement in the bbapi here. Leaving this open for now because it could be worth doing something here but removing all unneeded instances of size_t appears to be a pretty massive change. That could be an argument we should do it.