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/peer/peer.go

@@ -22,7 +22,9 @@ package peer
 
 import (
 	"context"
+	"fmt"
 	"net"
+	"strings"
 
 	"google.golang.org/grpc/credentials"
 )
@@ -39,6 +41,34 @@ type Peer struct {
 	AuthInfo credentials.AuthInfo
 }
 
+// String ensures the Peer types implements the Stringer interface in order to
+// allow to print a context with a peerKey value effectively.
+func (p *Peer) String() string {
+	if p == nil {
+		return "Peer<nil>"
+	}
+	sb := &strings.Builder{}
+	sb.WriteString("Peer{")
+	if p.Addr != nil {
+		fmt.Fprintf(sb, "Addr: '%s', ", p.Addr.String())
+	} else {
+		fmt.Fprintf(sb, "Addr: <nil>, ")
+	}
+	if p.LocalAddr != nil {
+		fmt.Fprintf(sb, "LocalAddr: '%s', ", p.LocalAddr.String())
+	} else {
+		fmt.Fprintf(sb, "LocalAddr: <nil>, ")
+	}
+	if p.AuthInfo != nil {
+		fmt.Fprintf(sb, "AuthInfo: '%s'", p.AuthInfo.AuthType())
+	} else {
+		fmt.Fprintf(sb, "AuthInfo: <nil>")
+	}
+	sb.WriteString("}")
+
+	return sb.String()
+}
+
 type peerKey struct{}
 
 // NewContext creates a new context with peer information attached.