driver: move Features and HostGatewayIP to specific driver

Adds a new HostGatewayIP entry in the Driver interface so we can
move Features and HostGatewayIP handling with cache to the very
specific driver (docker).

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

driver/driver.go

@@ -3,6 +3,7 @@ package driver
 import (
 	"context"
 	"io"
+	"net"
 
 	"github.com/docker/buildx/store"
 	"github.com/docker/buildx/util/progress"
@@ -60,6 +61,7 @@ type Driver interface {
 	Rm(ctx context.Context, force, rmVolume, rmDaemon bool) error
 	Client(ctx context.Context) (*client.Client, error)
 	Features(ctx context.Context) map[Feature]bool
+	HostGatewayIP(ctx context.Context) (net.IP, error)
 	IsMobyDriver() bool
 	Config() InitConfig
 }