Editor value is not preserved after serializing to HTML

[LaurelOlson]

Description

The following elements are not preserved when serializing editor state into HTML and then back into editor state:

• new lines in blockquotes
• new lines in codeblocks
• mentions

Steps

To reproduce:

• enter a multi-line blockquote and/or codeblock into sandbox along with a mention
• click "serialize"
• see the (1) serialized HTML and the (2) serialized HTML deserialized back into editor state

Sandbox

https://codesandbox.io/s/plate-playground-forked-rwfznn

Expectation

The editor value should be preserved when serialized to HTML and then deserialized back into editor state.

Environment

• slate: 0.76
• slate-react: 0.76
• browser: chrome

[LaurelOlson]

update: newlines in blockquotes are preserved if stripWhitespace: false is passed to serializeHtml and deserializeHtml (codesandbox updated). Newlines in code blocks and mentions are still not serialized properly.