feat: add 'ctx ls' command to list available cluster contexts in config

cmd/uncloud/context/root.go

@@ -0,0 +1,23 @@
+package context
+
+import (
+	"github.com/spf13/cobra"
+)
+
+func NewRootCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:     "context",
+		Aliases: []string{"ctx"},
+		Short:   "Switch between different cluster contexts. Contains subcommands to manage contexts.",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			// TODO
+			return nil
+		},
+	}
+
+	cmd.AddCommand(
+		NewListCommand(),
+	)
+
+	return cmd
+}