feat: add finch cp command (runfinch#135)

Issue #, if available: runfinch#82

*Description of changes:*
Added `finch cp` command and its e2e tests (runfinch/common-tests#11).

*Testing done:*
Unit tests and E2E tests.


- [X] I've reviewed the guidance in CONTRIBUTING.md


#### License Acceptance

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

Signed-off-by: Mrudul Harwani <[email protected]>

cmd/finch/nerdctl.go

@@ -129,6 +129,7 @@ var nerdctlCmds = map[string]string{
 	"compose":   "Compose",
 	"container": "Manage containers",
 	"create":    "Create a new container",
+	"cp":        "Copy files/folders between a running container and the local filesystem",
 	"events":    "Get real time events from the server",
 	"exec":      "Run a command in a running container",
 	"history":   "Show the history of an image",

e2e/e2e_test.go

@@ -59,6 +59,7 @@ func TestE2e(t *testing.T) {
 		tests.Run(&tests.RunOption{BaseOpt: o, CGMode: tests.Unified})
 		tests.Start(o)
 		tests.Stop(o)
+		tests.Cp(o)
 		tests.Tag(o)
 		tests.Save(o)
 		tests.Load(o)