platforms: move ToProto, FromProto to api/types

These utilities resulted in the platforms package to have the containerd
API as dependency. As this package is used in many parts of the code, as
well as external consumers, we should try to keep it light on dependencies,
with the potential to make it a standalone module.

These utilities were added in f3b7436b61,
which has not yet been included in a release, so skipping deprecation
and aliases for these.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/transfer/archive/exporter.go

@@ -156,7 +156,7 @@ func (iis *ImageExportStream) UnmarshalAny(ctx context.Context, sm streaming.Str
 		return err
 	}
 
-	specified := platforms.FromProto(s.Platforms)
+	specified := types.OCIPlatformFromProto(s.Platforms)
 	iis.stream = tstreaming.WriteByteStream(ctx, stream)
 	iis.mediaType = s.MediaType
 	iis.platforms = specified

pkg/transfer/image/imagestore.go

@@ -363,7 +363,7 @@ func (is *Store) MarshalAny(context.Context, streaming.StreamCreator) (typeurl.A
 		Labels:          is.imageLabels,
 		ManifestLimit:   uint32(is.manifestLimit),
 		AllMetadata:     is.allMetadata,
-		Platforms:       platforms.ToProto(is.platforms),
+		Platforms:       types.OCIPlatformToProto(is.platforms),
 		ExtraReferences: referencesToProto(is.extraReferences),
 		Unpacks:         unpackToProto(is.unpacks),
 	}
@@ -380,7 +380,7 @@ func (is *Store) UnmarshalAny(ctx context.Context, sm streaming.StreamGetter, a
 	is.imageLabels = s.Labels
 	is.manifestLimit = int(s.ManifestLimit)
 	is.allMetadata = s.AllMetadata
-	is.platforms = platforms.FromProto(s.Platforms)
+	is.platforms = types.OCIPlatformFromProto(s.Platforms)
 	is.extraReferences = referencesFromProto(s.ExtraReferences)
 	is.unpacks = unpackFromProto(s.Unpacks)