JSI codegen + implementation of `getCodeVersion()`.
Why?
We will need access to the `codeVersion` on the C++ side so we can include it as an argument to the `NewSession(...)` unary gRPC call. To avoid defining the code version in two places (`persist.js` and `CommCoreModule.h`), we'll define it in `CommCoreModule.h and access it on the JS side via this JSI function.
The next diff will replace usage of `codeVersion` from `persist.js` with a call to `global.CommCoreModule.getCodeVersion()`