Configure remark and rehype to render Markdown correctly

[jlvandenhout]

Currently the Markdown output that the editor produces differs from the original Markdown input, even when nothing is changed. The goal is to configure the HTML to Markdown pipeline such that it produces similar output if nothing is changed.

A list of inconsistencies that need to be fixed:

• [x] Support for code blocks highlighting
• [ ] List item marker should be - instead of *

[jlvandenhout]

To configure serialization to Markdown, have a look here

[jlvandenhout]

To allow highlighted code blocks and maintain editability we could follow the TipTap example here. Preserving information throughout the process of getting from Markdown to HTML and back to Markdown is still a challenge, especially the arguments following the first fence of the code block.