change: consider using ES10 sugar syntax

[eviltik]

1. Support classes: private, static & public members

Current syntax, we can't really define private / public methods/getter/setter/variable : everything is public.

class foo {
    constructor() {
        this.bar = true;
    }
}

The refactor will consist to separate public and private things, i.e

class foo {
   
    // private variable
    #foo_private= "bar_public";

    // public variable
    foo_public = "foo_public";

    constructor() {
        // modify private variable
        this.#foo_private = "bar2_private";
    
        // modify public variable
        this.foo_public = "bar2_public";

        // run a private method
        this.#myPrivateMethod();

        // run a public method
        this.myPublicMethod();
    }

    // private method
    #myPrivateMethod() {
    }

    // public method
    myPublicMethod() {
    }
}

2. Support classes: extend

Rather than something which is not currently used in all branches (i.e Prototype add/replace methods/variables, we should use something like this :

class CanvasText extends CanvasWidget {
}

3. Support classes: picking object notation

Rather than

let property;
if (object) {
    property = (typeof object.attribute != undefined) ? object.attribute : defaultValue;
}

We can (note the question mark)

const property = (typeof object?.attribute !== undefined) ? object.attribute : defaultValue;

4. All "Panels" (i.e Widget) should be a class

Not only ColorPicker, Keyboard, Slider ...

We should have Text, Button, Image