Switch to a containerized protoc for generated code

[haydentherapper]

Description

See https://github.com/namely/docker-protoc

This solves the issue of a mismatch between the locally installed protoc and the one used to check for updated generated code in the GHA workflow.

[bailey-coding]

Generating the protobuf clients with namely/protoc-all latest has some changes, which are probably somewhat expected, with the different versions of the various libraries.

I think it's because they update a few different things, and don't tag with protoc versions or other ones, but their own versions, but if we moved all uses to their version, at least we could use that consistently.

Here is the generated diff - https://gist.github.com/justbaileym/b9768410743c779fa2e3adb342478da5

I'm sure there are other places I need to update things in my branch, and my changes to the Makefile magic seem a bit janky

[haydentherapper]

Thanks for taking a look at this! Only concern is some of the swagger doc updates, though we saw something similar in #835, but I haven't had a chance to dig much into it.