Added OptionSetSpinnerColorCode to support color codes for spinners.

[polymorcodeus]

Added OptionSetSpinnerColorCode to pass in color code for spinner - is ignored if not set or if color codes is not enabled. It's not terribly visible but more of a completeness feature.

Example Usage:

	bar := progressbar.NewOptions64(
		-1,
		progressbar.OptionSetDescription("[Counter Example] Received"),
		progressbar.OptionSetWidth(10),
		progressbar.OptionEnableColorCodes(true),
		progressbar.OptionSetSpinnerColorCode("red"),
		progressbar.OptionThrottle(65*time.Millisecond),
		progressbar.OptionShowCount(),
		progressbar.OptionSpinnerType(14),
		progressbar.OptionFullWidth(),
		progressbar.OptionSetRenderBlankState(true),
	)

	c := make(chan int)

	go func(notify chan<- int) {
		defer close(notify)
		for i := 0; i < 100; i++ {
			c <- i
			time.Sleep(time.Millisecond * 100)
		}
	}(c)

	for v := range c {
		bar.Add(v)
	}