Convert CLI to urfave v2

Followed the Migration Guide at https://cli.urfave.org/migrate-v1-to-v2/
The major changes not pointed out in the migration guide are:
- context.Args() no longer produces a []slice, so context.Args().Slice()
  in substitued
- All cli.Global***** are deprecated (the migration guide is somewhat
  unclear on this)

Signed-off-by: Derek Nola <derek.nola@suse.com>

Vendor in urfave cli/v2

Signed-off-by: Derek Nola <derek.nola@suse.com>

Fix NewStringSlice calls

Signed-off-by: Derek Nola <derek.nola@suse.com>

cmd/ctr/commands/run/run_unix.go

@@ -39,43 +39,43 @@ import (
 	"github.com/containerd/platforms"
 	"github.com/intel/goresctrl/pkg/blockio"
 	"github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/urfave/cli"
+	"github.com/urfave/cli/v2"
 	"tags.cncf.io/container-device-interface/pkg/cdi"
 	"tags.cncf.io/container-device-interface/pkg/parser"
 )
 
 var platformRunFlags = []cli.Flag{
-	cli.StringFlag{
+	&cli.StringFlag{
 		Name:  "uidmap",
 		Usage: "Run inside a user namespace with the specified UID mapping range; specified with the format `container-uid:host-uid:length`",
 	},
-	cli.StringFlag{
+	&cli.StringFlag{
 		Name:  "gidmap",
 		Usage: "Run inside a user namespace with the specified GID mapping range; specified with the format `container-gid:host-gid:length`",
 	},
-	cli.BoolFlag{
+	&cli.BoolFlag{
 		Name:  "remap-labels",
 		Usage: "Provide the user namespace ID remapping to the snapshotter via label options; requires snapshotter support",
 	},
-	cli.BoolFlag{
+	&cli.BoolFlag{
 		Name:  "privileged-without-host-devices",
 		Usage: "Don't pass all host devices to privileged container",
 	},
-	cli.Float64Flag{
+	&cli.Float64Flag{
 		Name:  "cpus",
 		Usage: "Set the CFS cpu quota",
 		Value: 0.0,
 	},
-	cli.IntFlag{
+	&cli.IntFlag{
 		Name:  "cpu-shares",
 		Usage: "Set the cpu shares",
 		Value: 1024,
 	},
-	cli.StringFlag{
+	&cli.StringFlag{
 		Name:  "cpuset-cpus",
 		Usage: "Set the CPUs the container will run in (e.g., 1-2,4)",
 	},
-	cli.StringFlag{
+	&cli.StringFlag{
 		Name:  "cpuset-mems",
 		Usage: "Set the memory nodes the container will run in (e.g., 1-2,4)",
 	},
@@ -110,7 +110,7 @@ func NewContainer(ctx gocontext.Context, client *containerd.Client, context *cli
 		var (
 			ref = context.Args().First()
 			// for container's id is Args[1]
-			args = context.Args()[2:]
+			args = context.Args().Slice()[2:]
 		)
 		opts = append(opts, oci.WithDefaultSpec(), oci.WithDefaultUnixDevices)
 		if ef := context.String("env-file"); ef != "" {