c8d: Fix image commit with userns mapping (carry)
Alternative approach to #46938 as mentioned [here](https://github.com/moby/moby/pull/46938#issuecomment-1865249630).
daemon/containerd/image_snapshot_windows.go
package containerd

import (
	"context"

	"github.com/containerd/containerd/mount"
	"github.com/containerd/containerd/snapshots"
)

func (i *ImageService) remapSnapshot(ctx context.Context, snapshotter snapshots.Snapshotter, id string, parentSnapshot string) error {
	return nil
}

func (i *ImageService) unremapRootFS(ctx context.Context, mounts []mount.Mount) error {
	return nil
}

package containerd

import (
	"context"

	"github.com/containerd/containerd/mount"
	"github.com/containerd/containerd/snapshots"
)

const remapSuffix = "-remap"

func (i *ImageService) copyAndUnremapRootFS(ctx context.Context, dst, src []mount.Mount) error {
	return nil
}

func (i *ImageService) remapSnapshot(ctx context.Context, snapshotter snapshots.Snapshotter, id string, parentSnapshot string) error {
	return nil
}

func (i *ImageService) unremapRootFS(ctx context.Context, mounts []mount.Mount) error {
	return nil
}

nit; looks like this changed to a var in the windows variant; could you make this a `const` here as well? (and while doing so make it a single line, to keep `gofumpt` happy 😅)

```suggestion
const remapSuffix = "-remap"
```