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/github.com/moby/buildkit/client/llb/state.go

@@ -14,6 +14,7 @@ import (
 	"github.com/moby/buildkit/util/apicaps"
 	digest "github.com/opencontainers/go-digest"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	protobuf "google.golang.org/protobuf/proto"
 )
 
 type StateOption func(State) State
@@ -139,7 +140,7 @@ func (s State) SetMarshalDefaults(co ...ConstraintsOpt) State {
 func (s State) Marshal(ctx context.Context, co ...ConstraintsOpt) (*Definition, error) {
 	c := NewConstraints(append(s.opts, co...)...)
 	def := &Definition{
-		Metadata:    make(map[digest.Digest]pb.OpMetadata, 0),
+		Metadata:    make(map[digest.Digest]OpMetadata, 0),
 		Constraints: c,
 	}
 
@@ -157,7 +158,7 @@ func (s State) Marshal(ctx context.Context, co ...ConstraintsOpt) (*Definition,
 		return def, err
 	}
 	proto := &pb.Op{Inputs: []*pb.Input{inp}}
-	dt, err := proto.Marshal()
+	dt, err := protobuf.Marshal(proto)
 	if err != nil {
 		return def, err
 	}
@@ -210,7 +211,7 @@ func marshal(ctx context.Context, v Vertex, def *Definition, s *sourceMapCollect
 	}
 	vertexCache[v] = struct{}{}
 	if opMeta != nil {
-		def.Metadata[dgst] = mergeMetadata(def.Metadata[dgst], *opMeta)
+		def.Metadata[dgst] = mergeMetadata(def.Metadata[dgst], NewOpMetadata(opMeta))
 	}
 	s.Add(dgst, sls)
 	if _, ok := cache[dgst]; ok {
@@ -509,7 +510,7 @@ func (o *output) ToInput(ctx context.Context, c *Constraints) (*pb.Input, error)
 	if err != nil {
 		return nil, err
 	}
-	return &pb.Input{Digest: dgst, Index: index}, nil
+	return &pb.Input{Digest: string(dgst), Index: int64(index)}, nil
 }
 
 func (o *output) Vertex(context.Context, *Constraints) Vertex {
@@ -560,7 +561,7 @@ func (fn constraintsOptFunc) SetGitOption(gi *GitInfo) {
 	gi.applyConstraints(fn)
 }
 
-func mergeMetadata(m1, m2 pb.OpMetadata) pb.OpMetadata {
+func mergeMetadata(m1, m2 OpMetadata) OpMetadata {
 	if m2.IgnoreCache {
 		m1.IgnoreCache = true
 	}
@@ -654,12 +655,60 @@ func (cw *constraintsWrapper) applyConstraints(f func(c *Constraints)) {
 type Constraints struct {
 	Platform          *ocispecs.Platform
 	WorkerConstraints []string
-	Metadata          pb.OpMetadata
+	Metadata          OpMetadata
 	LocalUniqueID     string
 	Caps              *apicaps.CapSet
 	SourceLocations   []*SourceLocation
 }
 
+// OpMetadata has a more friendly interface for pb.OpMetadata.
+type OpMetadata struct {
+	IgnoreCache   bool                   `json:"ignore_cache,omitempty"`
+	Description   map[string]string      `json:"description,omitempty"`
+	ExportCache   *pb.ExportCache        `json:"export_cache,omitempty"`
+	Caps          map[apicaps.CapID]bool `json:"caps,omitempty"`
+	ProgressGroup *pb.ProgressGroup      `json:"progress_group,omitempty"`
+}
+
+func NewOpMetadata(mpb *pb.OpMetadata) OpMetadata {
+	var m OpMetadata
+	m.FromPB(mpb)
+	return m
+}
+
+func (m OpMetadata) ToPB() *pb.OpMetadata {
+	caps := make(map[string]bool, len(m.Caps))
+	for k, v := range m.Caps {
+		caps[string(k)] = v
+	}
+	return &pb.OpMetadata{
+		IgnoreCache:   m.IgnoreCache,
+		Description:   m.Description,
+		ExportCache:   m.ExportCache,
+		Caps:          caps,
+		ProgressGroup: m.ProgressGroup,
+	}
+}
+
+func (m *OpMetadata) FromPB(mpb *pb.OpMetadata) {
+	if mpb == nil {
+		return
+	}
+
+	m.IgnoreCache = mpb.IgnoreCache
+	m.Description = mpb.Description
+	m.ExportCache = mpb.ExportCache
+	if len(mpb.Caps) > 0 {
+		m.Caps = make(map[apicaps.CapID]bool, len(mpb.Caps))
+		for k, v := range mpb.Caps {
+			m.Caps[apicaps.CapID(k)] = v
+		}
+	} else {
+		m.Caps = nil
+	}
+	m.ProgressGroup = mpb.ProgressGroup
+}
+
 func Platform(p ocispecs.Platform) ConstraintsOpt {
 	return constraintsOptFunc(func(c *Constraints) {
 		c.Platform = &p