cli/command: replace EncodeAuthToBase64 for registry.EncodeAuthConfig

Replace uses of this function in favor of the implementation in the
API types, so that we have a single, canonical implementation.

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

cli/command/plugin/push.go

@@ -7,6 +7,7 @@ import (
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/command/image"
 	"github.com/docker/distribution/reference"
+	registrytypes "github.com/docker/docker/api/types/registry"
 	"github.com/docker/docker/pkg/jsonmessage"
 	"github.com/docker/docker/registry"
 	"github.com/pkg/errors"
@@ -55,8 +56,7 @@ func runPush(dockerCli command.Cli, opts pushOptions) error {
 		return err
 	}
 	authConfig := command.ResolveAuthConfig(ctx, dockerCli, repoInfo.Index)
-
-	encodedAuth, err := command.EncodeAuthToBase64(authConfig)
+	encodedAuth, err := registrytypes.EncodeAuthConfig(authConfig)
 	if err != nil {
 		return err
 	}