Core bsatn library

These files here are being used by both the Unreal C++ Client SDK and the Module Library. These files are the main files. The SDK do not use these files directly becouse a user might move the SDK plugin to the unreal engine plugin direcory or the unreal project directory. All changed made in one of the files should copied over to the SDK.

SDK bsatn path: "crates\sdk-unreal\SpacetimeDBSdk\Source\SpacetimeDBSdk\Public\BSATN"