feat: add cobra cmd to context

[raulb]

This could be useful on situations such as invoking a native cobra command (e.g.: help):

func (c *RootCommand) Execute(ctx context.Context) error {
	if c.flags.Version {
		_, _ = fmt.Fprintf(os.Stdout, "%s\n", conduit.Version(true))
		return nil
	}

	if cmd, ok := ctx.Value(ecdysis.CobraCtxCmd{}).(*cobra.Command); ok {
		return cmd.Help()
	}

	return nil
}

An alternative I had in mind was having another decorator named ExecuteWithCobraCommand which would be ExecuteWithCobraCommand(ctx context.Context, cmd *cobra.Command) error, but I'm not sure I'm in love with the idea of having two separate Execute methods. For situations like this one, it could be useful simply use the context.

[hariso]

LGTM! I had only one tiny thing to suggest.