feat(push): stub for 'image push' command and Dialer interface for cluster connectors

pkg/client/connector/tcp.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/netip"
 
+	"golang.org/x/net/proxy"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 )
@@ -29,6 +30,10 @@ func (c *TCPConnector) Connect(_ context.Context) (*grpc.ClientConn, error) {
 	return conn, nil
 }
 
+func (c *TCPConnector) Dialer() (proxy.ContextDialer, error) {
+	return nil, fmt.Errorf("proxy connections are not supported over a TCP connection")
+}
+
 func (c *TCPConnector) Close() error {
 	return nil
 }