Tips for using protobuf @ head with bazel

[Jeffrey Baker]

Is it practical to develop using protobuf from head, or a recent release, in a bazel project? I've run into several issues that I don't know how to overcome, so I'd be glad to hear any experiences, tips, and advice. The first problem I've run into is that in bazel 7, or bazel 6 with bzlmod enabled, silently uses protoc 3.19.6 instead of the protoc from the protobuf library I want to use. This can lead to either noisy failures to build, or sneaky failures like ignoring ctype=CORD. Another problem is that if I want to use editions, I need to pass a flag to protoc, and as far as I can find bazel provides no means of passing flags to protoc that is analogous to `copt`. 

`proto_lang_toolchain` seems like it might be on point but the docs only discuss Java and I can't find a project on github that seems to be using the feature for C++.