[Bug] Softline breaks and paragraphs aren't properly persed

[TatsuUkraine]

Bug Description

This basically continuation of this issue. #912
It seems editor still doesn't recognize softlines. Also after some update it actually converts paragraphs into the softline breaks during convert from MD format into the document

How to Reproduce

1. use entry line like First paragraph.\n\nSecond pargraph
2. initialize editor using markdownToDocument function
3. convert editor document back to MD format using documentToMarkdown function

Output will be First paragraph.\nSecond pargraph, which 1 paragraph with softline break inside

Expected Behavior

Output should be First paragraph.\n\nSecond pargraph

Operating System

Any

AppFlowy Editor Version(s)

v4, v5

Screenshots

No response

Additional Context

No response