gitserver: Allow non-utf-8 refnames in ListRefs API (#61988)

We recently saw an alert for this on dotcom, refnames can be non utf-8 as well so we have to switch to bytes for this field.

Test plan:

Round trip test still passes.

Author: eseliger

cmd/gitserver/internal/server_grpc_test.go

@@ -907,7 +907,7 @@ func TestGRPCServer_ListRefs(t *testing.T) {
 		}
 		if diff := cmp.Diff([]*v1.GitRef{
 			{
-				RefName:   "refs/heads/master",
+				RefName:   []byte("refs/heads/master"),
 				CreatedAt: timestamppb.New(time.Time{}),
 			},
 		}, refs, cmpopts.IgnoreUnexported(v1.GitRef{}, timestamppb.Timestamp{})); diff != "" {

internal/gitserver/commands_test.go

@@ -2067,7 +2067,7 @@ func TestClient_ListRefs(t *testing.T) {
 				ss.RecvFunc.SetDefaultReturn(nil, io.EOF)
 				ss.RecvFunc.PushReturn(&proto.ListRefsResponse{Refs: []*proto.GitRef{
 					{
-						RefName:      "refs/heads/master",
+						RefName:      []byte("refs/heads/master"),
 						TargetCommit: "deadbeef",
 						CreatedAt:    timestamppb.New(now),
 					},

internal/gitserver/gitdomain/common.go

@@ -417,8 +417,8 @@ type Ref struct {
 
 func RefFromProto(r *proto.GitRef) Ref {
 	return Ref{
-		Name:        r.GetRefName(),
-		ShortName:   r.GetShortRefName(),
+		Name:        string(r.GetRefName()),
+		ShortName:   string(r.GetShortRefName()),
 		Type:        RefTypeFromProto(r.GetRefType()),
 		CommitID:    api.CommitID(r.GetTargetCommit()),
 		RefOID:      api.CommitID(r.GetRefOid()),
@@ -429,8 +429,8 @@ func RefFromProto(r *proto.GitRef) Ref {
 
 func (r *Ref) ToProto() *proto.GitRef {
 	return &proto.GitRef{
-		RefName:      r.Name,
-		ShortRefName: r.ShortName,
+		RefName:      []byte(r.Name),
+		ShortRefName: []byte(r.ShortName),
 		TargetCommit: string(r.CommitID),
 		RefOid:       string(r.RefOID),
 		CreatedAt:    timestamppb.New(r.CreatedDate),

internal/gitserver/v1/gitserver.pb.go

@@ -278,10 +278,10 @@ message ListRefsResponse {
 
 message GitRef {
   // ref_name is the unabbreviated name of the reference, i.e., refs/heads/main, or refs/tags/1.0.
-  string ref_name = 1;
+  bytes ref_name = 1;
   // short_ref_name is the abbreviated name of the reference, if unambiguous.
   // I.e., main, or 1.0.
-  string short_ref_name = 2;
+  bytes short_ref_name = 2;
   // target_commit is the hash of the commit the reference is currently pointing at.
   // For a head reference, this is the commit the head is currently pointing at.
   // For a tag, this is the commit that the tag is attached to.