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/balancer/balancer.go

@@ -30,6 +30,7 @@ import (
 	"google.golang.org/grpc/channelz"
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials"
+	estats "google.golang.org/grpc/experimental/stats"
 	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/internal"
 	"google.golang.org/grpc/metadata"
@@ -54,13 +55,14 @@ var (
 // an init() function), and is not thread-safe. If multiple Balancers are
 // registered with the same name, the one registered last will take effect.
 func Register(b Builder) {
-	if strings.ToLower(b.Name()) != b.Name() {
+	name := strings.ToLower(b.Name())
+	if name != b.Name() {
 		// TODO: Skip the use of strings.ToLower() to index the map after v1.59
 		// is released to switch to case sensitive balancer registry. Also,
 		// remove this warning and update the docstrings for Register and Get.
 		logger.Warningf("Balancer registered with name %q. grpc-go will be switching to case sensitive balancer registries soon", b.Name())
 	}
-	m[strings.ToLower(b.Name())] = b
+	m[name] = b
 }
 
 // unregisterForTesting deletes the balancer with the given name from the
@@ -71,8 +73,21 @@ func unregisterForTesting(name string) {
 	delete(m, name)
 }
 
+// connectedAddress returns the connected address for a SubConnState. The
+// address is only valid if the state is READY.
+func connectedAddress(scs SubConnState) resolver.Address {
+	return scs.connectedAddress
+}
+
+// setConnectedAddress sets the connected address for a SubConnState.
+func setConnectedAddress(scs *SubConnState, addr resolver.Address) {
+	scs.connectedAddress = addr
+}
+
 func init() {
 	internal.BalancerUnregister = unregisterForTesting
+	internal.ConnectedAddress = connectedAddress
+	internal.SetConnectedAddress = setConnectedAddress
 }
 
 // Get returns the resolver builder registered with the given name.
@@ -232,8 +247,8 @@ type BuildOptions struct {
 	// implementations which do not communicate with a remote load balancer
 	// server can ignore this field.
 	Authority string
-	// ChannelzParentID is the parent ClientConn's channelz ID.
-	ChannelzParentID *channelz.Identifier
+	// ChannelzParent is the parent ClientConn's channelz channel.
+	ChannelzParent channelz.Identifier
 	// CustomUserAgent is the custom user agent set on the parent ClientConn.
 	// The balancer should set the same custom user agent if it creates a
 	// ClientConn.
@@ -242,6 +257,10 @@ type BuildOptions struct {
 	// same resolver.Target as passed to the resolver. See the documentation for
 	// the resolver.Target type for details about what it contains.
 	Target resolver.Target
+	// MetricsRecorder is the metrics recorder that balancers can use to record
+	// metrics. Balancer implementations which do not register metrics on
+	// metrics registry and record on them can ignore this field.
+	MetricsRecorder estats.MetricsRecorder
 }
 
 // Builder creates a balancer.
@@ -409,6 +428,9 @@ type SubConnState struct {
 	// ConnectionError is set if the ConnectivityState is TransientFailure,
 	// describing the reason the SubConn failed.  Otherwise, it is nil.
 	ConnectionError error
+	// connectedAddr contains the connected address when ConnectivityState is
+	// Ready. Otherwise, it is indeterminate.
+	connectedAddress resolver.Address
 }
 
 // ClientConnState describes the state of a ClientConn relevant to the