protobuf: remove gogoproto

Removes gogo/protobuf from buildx and updates to a version of
moby/buildkit where gogo is removed.

This also changes how the proto files are generated. This is because
newer versions of protobuf are more strict about name conflicts. If two
files have the same name (even if they are relative paths) and are used
in different protoc commands, they'll conflict in the registry.

Since protobuf file generation doesn't work very well with
`paths=source_relative`, this removes the `go:generate` expression and
just relies on the dockerfile to perform the generation.

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

vendor/google.golang.org/grpc/internal/grpcsync/callback_serializer.go

@@ -53,16 +53,28 @@ func NewCallbackSerializer(ctx context.Context) *CallbackSerializer {
 	return cs
 }
 
-// Schedule adds a callback to be scheduled after existing callbacks are run.
+// TrySchedule tries to schedules the provided callback function f to be
+// executed in the order it was added. This is a best-effort operation. If the
+// context passed to NewCallbackSerializer was canceled before this method is
+// called, the callback will not be scheduled.
 //
 // Callbacks are expected to honor the context when performing any blocking
 // operations, and should return early when the context is canceled.
+func (cs *CallbackSerializer) TrySchedule(f func(ctx context.Context)) {
+	cs.callbacks.Put(f)
+}
+
+// ScheduleOr schedules the provided callback function f to be executed in the
+// order it was added. If the context passed to NewCallbackSerializer has been
+// canceled before this method is called, the onFailure callback will be
+// executed inline instead.
 //
-// Return value indicates if the callback was successfully added to the list of
-// callbacks to be executed by the serializer. It is not possible to add
-// callbacks once the context passed to NewCallbackSerializer is cancelled.
-func (cs *CallbackSerializer) Schedule(f func(ctx context.Context)) bool {
-	return cs.callbacks.Put(f) == nil
+// Callbacks are expected to honor the context when performing any blocking
+// operations, and should return early when the context is canceled.
+func (cs *CallbackSerializer) ScheduleOr(f func(ctx context.Context), onFailure func()) {
+	if cs.callbacks.Put(f) != nil {
+		onFailure()
+	}
 }
 
 func (cs *CallbackSerializer) run(ctx context.Context) {