fontBoundingBox is not implemented

## Issue or Feature
- [x] If this is an issue with installation, I have read the [troubleshooting guide](https://github.com/Automattic/node-canvas/issues/1511).

Hi! I was expecting to use fontBoundingBox, but as it turns out there's a TODO in code left and it isn't done. I saw some PR's that said it couldn't be done. Could there be some kind of resolution or workaround to experience the same effect as fontBoundingBox?

In the visible image, I would like to get the blue part. (fontBoundingBox)
## Steps to Reproduce
```js
import Canvas from 'canvas';

const canvas = Canvas.createCanvas(10, 10);

const ctx = canvas.getContext('2d')
const measure = ctx.measureText("woohoo!");

console.log(measure.fontBoundingBoxAscent) // undefined :(
```

## Your Environment
* Version of node-canvas (output of `npm list canvas` or `yarn list canvas`): canvas@2.8.0
* Environment (e.g. node 4.2.0 on Mac OS X 10.8): v16.4.2 on Windows