cmd: don't alias context package, and use cliContext for cli.Context

Unfortunately, this is a rather large diff, but perhaps worth a one-time
"rip off the bandaid" for v2. This patch removes the use of "gocontext"
as alias for stdLib's "context", and uses "cliContext" for uses of
cli.context.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cmd/ctr/commands/namespaces/namespaces_other.go

@@ -23,6 +23,6 @@ import (
 	"github.com/urfave/cli/v2"
 )
 
-func deleteOpts(context *cli.Context) []namespaces.DeleteOpts {
+func deleteOpts(cliContext *cli.Context) []namespaces.DeleteOpts {
 	return nil
 }