Check for breaking proto changes

[dnr]

What changed?

• Add (back) make target buf-breaking to run buf's breaking proto changes check against the parent commit and the main branch.
• Add buf-breaking to ci-build-misc so it runs in CI.
• Fix goimports target to use shell variables instead of git variables to make make faster, and also fix the binary name (was just broken).

Why?

Detecting breaking proto changes early avoids bugs.

How did you test it?

Manual testing with deliberate breaking changes.

[dnr]

I removed the buf upgrade from this PR. I couldn't get buf 1.32.2 to respect a config file (to change the compatibility level and add ignores) when using binpb inputs after trying many many combinations of flags and things. buf 1.6.0 respects the config file :shrug:

[dnr]

I removed the buf upgrade from this PR. I couldn't get buf 1.32.2 to respect a config file (to change the compatibility level and add ignores) when using binpb inputs after trying many many combinations of flags and things. buf 1.6.0 respects the config file 🤷

I filed a bug against buf and they fixed it. It'll probably be in buf 1.35.0. After that we can upgrade buf to use v2 configs if desired (but no rush)

[dnr]

I think this PR is broken.. GH is no longer running tests on push. Going to close/reopen to see if that fixes it

[dnr]

Still not running tests, going to try with a new PR