Add template to generate protocol buffers

[compiletime]

Given the C++ type:

struct Data {
  std::string x;
  int y;
  std::vector<int> z;
};

Generate a .proto file including (assuming 64 bit):

message Data {
  required string x = 1;
  required int64 y = 2;
  repeated int64 z = 3;
}

Generate a .h file including:

std::vector<std::byte> serialize(Data);

std::optional<Data> deserialize(std::vector<std::byte>);

[jbcoe]

I'm unconvinced that there's any point in this.

protobuffers allow one to specify an exchange format from a .proto file. C++, C#, Python etc can be generated from the .proto file by protoc. I'm not sure how FFIG would fit into this picture.

I'd favour closing this issue as "Will not fix".

[compiletime]

I've updated the description to give an example of what this might do. I opened this alongside https://github.com/FFIG/ffig/issues/306, with the intent of using FFIG to automate writing serialization and deserialization.

I hadn't given any thought to how protobuf interacts with other languages. Mostly I meant to use it for its binary serialization.

[jbcoe]

Would adding support for some sort of serialization achieve the same goal?