Resetting blockquote should split lines into paragraphs

[12joan]

Description

When resetting a blockquote containing multiple lines (separated by \n, as is normal for blockquotes), it turns into a single paragraph with all the lines inside it, rather than one paragraph for each line.

Steps

1. Go to the sandbox
2. Create a blockquote with multiple lines
3. Place cursor at start of blockquote
4. Press backspace to reset the blockquote to a paragraph

Sandbox

https://codesandbox.io/s/sandpack-project-forked-dysl1n

Expectation

A new paragraph is created for each line of the blockquote.

Environment

• slate: 0.88.1
• slate-react: 0.82.1
• browser: Firefox

_P-190

Funding

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• We receive the pledge once the issue is completed & verified

[zbeyens]

I'm not sure what's the standard around this. Notion keeps the new lines in a single paragraph. For this issue, let's add an option to enable this behavior for now.