feat: mosaic (halfblocks graphics) support

[raphamorim]

Original PR: charmbracelet/x#387

Convert images to strings using half blocks symbols

TODO

• Rework API to mosaic.New().Width(100).Height(40).Render(img)
• Use draw.Scaler
• Use draw.FloydSteinberg

Added examples

Simple Example

func main() {
	dogImg, err := loadImage("./pekinas.jpg")
	if err != nil {
		fmt.Print(err)
		os.Exit(1)
	}

	m := mosaic.New().Width(80).Height(80).Scale(2)

	fmt.Println(lipgloss.JoinVertical(lipgloss.Right, lipgloss.JoinHorizontal(lipgloss.Center, m.Render(dogImg))))
}

Scaling

Scales uses bilinear, which works at least as well as the others do in every situation. So prob use Bilinear for upscaling and downscaling as default.

scaling 1x and 2x:

Other examples

[aymanbagabas]

The goal here is to make both mosaic.New() and mosaic.Mosaic{} return the same thing

[raphamorim]

Regarding mosaic, I think would be good to support MaxWidth and MaxHeight, so people can create constraints for one or both and allow mosaic do the image perspective calculation cc @aymanbagabas @meowgorithm .

The new width/height API forces the dev to write the exact (or approximate) width/height and it can be quite tedious/unhandy job.