Feature: Add Render setting in Every Toolbox and Custom plugins

## Summary
Since I made custom plugins/extensions I met difficulties to add render setting that I have been created before to another custom extension.

## Idea
My idea is to activate the render setting that I have created before on every toolbox.

## Example
1. I add an official editors extension such as Paragraph
2. I have a render setting that the inside has
- font family
- line-height
- font size
- etc.

```
paragraph: {
class: Paragraph,
inlineToolbar: true,
Setting: CustomSetting
},
```
So, when I click the Paragraph toolbox my custom setting will appear and mix to paragraph setting.

## Cons
It's very weird if I extend the custom setting class or I copy and paste the custom setting frequently to another toolbox extension code.