Render block references/embeds in formatted view

[Stvad]

I know that it's a deficit of the Roam markdown export, but I given that we have access to the json one as well, I believe this can be remediated on the exporter side.

[MatthieuBizien]

Renderer from the markdown will always be limited. The long-term view is to use only the JSON. I'm not sure a mixed renderer could be done in a robust and non-bloated way.