[Bug] Breaks ignored when converting HTML

### Bug Description

When converting an HTML document to an editor document, breaks are stripped from the editor document.

### How to Reproduce

Attempt to reimport HTML that is exported from the editor and includes `br` tags.

### Expected Behavior

Break tags are properly parsed into empty lines.

### Operating System

MacOS

### AppFlowy Editor Version(s)

2.3.4

### Screenshots

_No response_

### Additional Context

_No response_