libct/devices: move config to libct/cg/devices/config

Currently, libcontainer/devices contains two things:

1. Device-related configuration data structures and accompanying
   methods. Those are used by runc itself, mostly by libct/cgroups.

2. A few functions (HostDevices, DeviceFromPath, GetDevices).
   Those are not used by runc directly, but have some external users
   (cri-o, microsoft/hcsshim), and they also have a few forks
   (containerd/pkg/oci, podman/pkg/util).

This commit moves (1) to a new separate package, config (under
libcontainer/cgroups/devices), adding a backward-compatible aliases
(marked as deprecated so we will be able to remove those later).

Alas it's not possible to move this to libcontainer/cgroups directly
because some IDs (Type, Rule, Permissions) are too generic, and renaming
them (to DeviceType, DeviceRule, DevicePermissions) will break backward
compatibility (mostly due to Rule being embedded into Device).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/devices/device_unix.go

@@ -19,13 +19,6 @@ var (
 	osReadDir = os.ReadDir
 )
 
-func mkDev(d *Rule) (uint64, error) {
-	if d.Major == Wildcard || d.Minor == Wildcard {
-		return 0, errors.New("cannot mkdev() device with wildcards")
-	}
-	return unix.Mkdev(uint32(d.Major), uint32(d.Minor)), nil
-}
-
 // DeviceFromPath takes the path to a device and its cgroup_permissions (which
 // cannot be easily queried) to look up the information about a linux device
 // and returns that information as a Device struct.