feat: buf bsr

[moritzzimmer]

what

PoC to test buf's maven remote packages (see https://buf.build/docs/bsr/remote-packages/maven/).

see https://buf.build/stroeer/tapir/assets/main for assets

learnings

✅ buf's remote packages are separated for proto and grpc per default
✅ packages build for various proto and grpc versions are available
✅ we could remove the java package release process in tapir and simplify our tools
✅ registries for node and go are available as well (not tested in this poc)
✅ automatic documentation is nice and we could simplify our docs toolchain, see https://buf.build/stroeer/tapir/docs/main

🟡 we can't specifiy custom tag values for default buf push GitHub action (we could create a custom make target though)
🟡 free plan is up to 100 types (according to buf beta price we currently have 63)

❌ packages names are different (see large diff in https://github.com/stroeer/paperboy/pull/1984) and can't be changed easily atm, see bufbuild/plugins#636

outcome

I would push to the BSR to use the documentation but stick to remote plugins for code generation for now)