Move onnx.proto3 to ModelProtoFileReader module and add a batch file to generate the code
Delete ONNXProto3, ONNXAndProtobufHelper, & old ThirdParty protobuf module
Wrap some code with WITH_PROTOBUF until Linux protobuf libraries are supported
Use toolchain v140 instead of v142 to fix Clang unresolved external symbols
#preflight 609ed376046b9d00015b1322
#rb Gines.Hidalgo
[CL 16336440 by Joe Kirchoff in ue5-main branch]
