[Bug] copy-and-paste formatted text does not preserve formatting

Steps to reproduce:
1. Add text to editor instance
2. Select a word and make it bold
3. Select another word and make it a link
4. Highlight the text
5. Add a new text block, and paste the text
6. Note that the text is pasted in without the bold formatting and link, and is also missing the space between the bolded word and the linked word (see screenshot)

Expected behavior:
* the pasted text includes the bold formatting and link, and the space between the bolded word and linked word

Screenshots:

Device, Browser, OS: Macbook with Mojave 10.14.6 , Firefox Dev Edition 90.0b12

Editor.js version: 2.22.1

Plugins you use with their versions:

```
"@editorjs/embed": "2.4.0",
"@editorjs/header": "2.6.1",
"@editorjs/list": "1.6.2",
"@editorjs/paragraph": "2.8.0",
"@editorjs/underline": "1.0.0",
"editorjs-strikethrough": "0.0.1",
"editorjs-undo": "0.1.4",
"@stfy/react-editor.js": "1.0.3",
```