feature: Access to Markdown and Raw data

[phenomen]

Problem: there is no way to easily access Markdown and Raw data of the Editor component. Raw Tiptap nodes are available in the localStorage, while Markdown is only accessible with manual copy-paste from the Editor.

Possible solution: Expose those props similar to props on Melt components.

[multiplehats]

In my app where I'm using Tiptap, I store the HTML (for seo purposes when loading on the server) and the JSON for editing purpose in 2 tables. So exposing most of the tiptap stuff would be incredibly helpful

[fermellone]

There is a tiptap extension that converts the content to markdown.
https://github.com/aguingand/tiptap-markdown