[Feature] Add ability to display multi-line text in regular cells

[elia-ba]

Initial checklist

• Is this really a problem?
• I have searched the Github Issues for similar issues, but did not find anything.

Problem

Right now the only way to display multi-line text is to use a rich text document in the cell.
This has massive drawbacks however:

1. it's extremely slow, the grid takes 20x the amount of time to load
2. it's cumbersome having to parse the text in order to extract the paragraphs
3. the rich text format could add unwanted formatting codes to text that is supposed to be plain text

The normal cells should support multi-line text, Excel has this and so does Google Sheets.