Adds Recomb for ImageRef

[n0vad3v]

This PR will add support for vips_recomb on ImageRef, will provide similar functionality as sharp does(https://sharp.pixelplumbing.com/api-operation#recomb)

Sharp example:

sharp(input)
  .recomb([
   [0.3588, 0.7044, 0.1368],
   [0.2990, 0.5870, 0.1140],
   [0.2392, 0.4696, 0.0912],
  ])
  .raw()
  .toBuffer(function(err, data, info) {
    // data contains the raw pixel data after applying the matrix
    // With this example input, a sepia filter has been applied
  });

Go example after this PR merged:

package main

import (
	"fmt"
	"os"

	"github.com/davidbyttow/govips/v2/vips"
)

func main() {
	vips.Startup(nil)
	defer vips.Shutdown()

	img, _ := vips.NewImageFromFile("test.png")
	matrix := [][]float64{
		{0.3588, 0.7044, 0.1368},
		{0.2990, 0.5870, 0.1140},
		{0.2392, 0.4696, 0.0912},
	}

	err := img.Recomb(matrix)
	if err != nil {
		fmt.Println(err)
	}
	image1bytes, _, _ := img.ExportPng(vips.NewPngExportParams())
	_ = os.WriteFile("experiment.png", image1bytes, 0644)

}

test.png

experiment.png

[tonimelisma]

lgtm