The Google C++ protobuf implementation has issues with dynamic linkage across DLL boundaries because it uses global variables. It also has a compile-time dependency because the protoc version must exactly match the libprotobuf version. Using nanopb with a customized generator fixes both of these issues.
Co-authored-by: Gold856 <117957790+Gold856@users.noreply.github.com>
Reverts #6609 since that fix didn't Just Work(tm) on Windows. (edit: or Ubuntu. Seems to have broken everything except macOS.) This PR configures CMake to try and find protobuf-config.cmake first, which allows protobuf to pull in abseil for us. If protobuf-config.cmake is not available (coprocessors which don't have a new enough protobuf installed are a common case), it will fallback to CMake's built-in FindProtobuf module, which is what we were using before.
Add wpi::CreateMessage, a wrapper with an ifdef to switch between Arena::CreateMessage and Arena::Create, since the former is deprecated in newer versions of protobuf. This allows forward compatibility with newer versions of protobuf.
