Merge pull request #10658 from darwin-containers/reorganize-mount-unmount

Reorganize mount/unmount code so it is easier to add Darwin-specific implementation

pkg/os/mount_unix.go

@@ -20,11 +20,12 @@ package os
 
 import (
 	"github.com/containerd/containerd/v2/core/mount"
+	"github.com/containerd/errdefs"
 )
 
 // Mount will call unix.Mount to mount the file.
 func (RealOS) Mount(source string, target string, fstype string, flags uintptr, data string) error {
-	return mount.ErrNotImplementOnUnix
+	return errdefs.ErrNotImplemented
 }
 
 // Unmount will call Unmount to unmount the file.