Add custom font

Hello,

I went through, the following GitHub issues: #857 #1622 #1215

Almost all of the issues, though a little different, provide a way to add font family to the list.

Most common way to tackle, as far as I've understood:

let styleManager = this.editor.StyleManager;
let typographySector = styleManager.getSector('Typography');
let fontProperty = styleManager.getProperty('Typography', 'font-family');

... Add fonts then

const styleManager = editor.StyleManager;
const fontProperty = styleManager.getProperty('Typography', 'font-family');

... Add fonts then

For both of this, I'm getting the typographySector and fontProperty as undefined. I don't know, if I'm doing something incorrect or, if I'm incorrectly implementing them.

Here's my snippet, of what I'm trying.

editor.on('load', () => {
      const styleManager = editor.StyleManager;
      const fontProperty = styleManager.getProperty('Typography', 'font-family');
      const typographySector = styleManager.getSector('Typography');
      console.log({fontProperty, typographySector}); // both are returned undefined
})

Thanks for putting your time on this.