Ensure HyperV 9p mounts work when a dir doesn't exist

Before, we required that the mount target exist and be a
directory for the 9p mount to successfully complete, which is not
how things are supposed to work - the user should be able to
mount anywhere. This should just be a simple mkdir, but with FCOS
the root directory is immutable so we need to undo that before we
can mkdir, and unfortunately we don't have a library that can do
chattr (and I didn't want to drag in a new dependency just for
that), so let's be gross and add it to the SSH command. I
aggressively dislike this but it does work.

[NO NEW TESTS NEEDED] Can worry about getting a more generic
mount test together for Machine later.

Signed-off-by: Matt Heon <mheon@redhat.com>

pkg/machine/hyperv/volumes.go

@@ -5,6 +5,7 @@ package hyperv
 import (
 	"errors"
 	"fmt"
+	"path"
 
 	"github.com/containers/podman/v5/pkg/machine"
 	"github.com/containers/podman/v5/pkg/machine/hyperv/vsock"
@@ -40,7 +41,19 @@ func removeShares(mc *vmconfigs.MachineConfig) error {
 
 func startShares(mc *vmconfigs.MachineConfig) error {
 	for _, mount := range mc.Mounts {
-		args := []string{"-q", "--", "sudo", "podman"}
+		args := []string{"-q", "--"}
+
+		cleanTarget := path.Clean(mount.Target)
+		requiresChattr := !strings.HasPrefix(cleanTarget, "/home") && !strings.HasPrefix(cleanTarget, "/mnt")
+		if requiresChattr {
+			args = append(args, "sudo", "chattr", "-i", "/", "; ")
+		}
+		args = append(args, "sudo", "mkdir", "-p", cleanTarget, "; ")
+		if requiresChattr {
+			args = append(args, "sudo", "chattr", "+i", "/", "; ")
+		}
+
+		args = append(args, "sudo", "podman"}
 		if logrus.IsLevelEnabled(logrus.DebugLevel) {
 			args = append(args, "--log-level=debug")
 		}