Move from buf image build -o - to buf protoc

[bufdev]

Note we haven't documented it yet, but buf protoc is now integrated into buf, and would replace much of your logic piping the output of buf image build -o - to protoc --descriptor_set_in - would recommend checking it out! It's a drop-in replacement to protoc, but does use protoc for the builtin plugins java, cpp, etc.

[bufdev]

Note you can now use buf generate https://docs.buf.build/generate-usage