Add editions support

[Mitchman215]

Summary

Stay up-to-date with recent protobuf changes

What is the feature request for?

The core library

The Problem

Currently, if I try to run protoc with betterproto2 on a .proto file that has edition = "2023";, it fails. Here's exact repro behavior:

Make test.proto file:

edition = "2023";

message Hi {
  uint32 foo = 1;
}

Run protoc on it:

protoc --python_betterproto2_out=out test.proto 

Currently, this gives the following console output:

Writing __init__.py
test.proto: is an editions file, but code generator protoc-gen-python_betterproto2 hasn't been updated to support editions yet.  Please ask the owner of this code generator to add support or switch back to proto2/proto3.

See https://protobuf.dev/editions/overview/ for more information.--python_betterproto2_out:

For context, I am using betterproto2-compiler version 0.9.0 and libprotoc version 33.4

The Ideal Solution

Implement editions support, allowing python code generation from .proto files that uses something like edition = "2023"; as opposed to syntax = "proto3";

The Current Solution

Use proto2/proto3 instead of editions.