Support for color (OpenType SVG) fonts

## Issue or Feature

It would be great to support colored fonts like these: https://www.colorfonts.wtf/. If these are used now, they just take on the fill color.

```
const fs = require('fs')
const { createCanvas, registerFont } = require('canvas')
const { buildResponse, handleError } = require('./utils')
registerFont('./fonts/gilbert-color.otf', { family: 'Gilbert Color' })

module.exports.canvasTest = async (event) => {
const canvas = createCanvas(200, 200)
const ctx = canvas.getContext('2d')
ctx.font = '12px "Gilbert Color"'
ctx.fillText('Awesome!', 50, 100)

const buf = canvas.toBuffer();
fs.writeFileSync("test.png", buf);
// return buildResponse('test.png')
}
```

Results in