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/preloader.go

@@ -20,6 +20,7 @@ package grpc
 
 import (
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/status"
 )
 
@@ -31,9 +32,10 @@ import (
 // later release.
 type PreparedMsg struct {
 	// Struct for preparing msg before sending them
-	encodedData []byte
+	encodedData mem.BufferSlice
 	hdr         []byte
-	payload     []byte
+	payload     mem.BufferSlice
+	pf          payloadFormat
 }
 
 // Encode marshalls and compresses the message using the codec and compressor for the stream.
@@ -57,11 +59,27 @@ func (p *PreparedMsg) Encode(s Stream, msg any) error {
 	if err != nil {
 		return err
 	}
-	p.encodedData = data
-	compData, err := compress(data, rpcInfo.preloaderInfo.cp, rpcInfo.preloaderInfo.comp)
+
+	materializedData := data.Materialize()
+	data.Free()
+	p.encodedData = mem.BufferSlice{mem.NewBuffer(&materializedData, nil)}
+
+	// TODO: it should be possible to grab the bufferPool from the underlying
+	//  stream implementation with a type cast to its actual type (such as
+	//  addrConnStream) and accessing the buffer pool directly.
+	var compData mem.BufferSlice
+	compData, p.pf, err = compress(p.encodedData, rpcInfo.preloaderInfo.cp, rpcInfo.preloaderInfo.comp, mem.DefaultBufferPool())
 	if err != nil {
 		return err
 	}
-	p.hdr, p.payload = msgHeader(data, compData)
+
+	if p.pf.isCompressed() {
+		materializedCompData := compData.Materialize()
+		compData.Free()
+		compData = mem.BufferSlice{mem.NewBuffer(&materializedCompData, nil)}
+	}
+
+	p.hdr, p.payload = msgHeader(p.encodedData, compData, p.pf)
+
 	return nil
 }