protobuf: remove gogoproto

[jsternberg]

Fixes #3119

Remove gogoproto in favor of the standard protobuf compiler. This
removes any nonstandard extensions that were part of gogoproto such as
the custom types.

Re-spin of #4422

[jsternberg]

Separating the vtproto component of this into a separate PR.

[jsternberg]

We did some investigation of memory usage when transferring a large context and found some interesting stuff. The big thing we found is that a certain optimization utilized here does nothing and doesn't help with memory usage. This is because of the default grpc codec and is seen across different implementations.

The default codec will always call Reset on the underlying message. This can be seen here. The Merge is set to false by default so the reset always happens. The implementation of reset in gogo/protobuf removes the saved buffer so we always allocate memory for the data we are transferring.

This behavior is consistent with the standard go implementation which does the same thing, but it seems the standard implementation benefits a little bit from utilizing a v2 version of the codec that incorporates a memory pool. Still, it allocates a lot and that dominates the performance.

vtproto also does the same thing if you do the same thing, but vtproto can generate its own reset function that's useful for memory pools and we can also customize the codec to remove the reset if that makes sense. Either way, I haven't seen a regression in the performance so far but I think we can like do much more with vtproto if we dive into things more thoroughly.

[kzys]

Great. Finally! Looks good to me change-wise. You still need to address the test failures though.

I'll close my PR.

[crazy-max]

this replace can be removed and just need to update github.com/tonistiigi/fsutil now that tonistiigi/fsutil#206 is merged?

[thompson-shaun]

Thanks for laying all the groundwork for this @kzys -- happy it was finally addressed.