Option to syntax highlight only fenced code blocks as code blocks; properly highlight admonitions / content tabs

[skwde]

This would greatly improve the syntax highlighting and fix numerous highlighting issues, e.g. in python markdown.

It would e.g. allow to properly highlight admonitions and content tabs (as they e.g. appear in mkdocs material)
Following a example admonition which gets highlighted incorrectly.

!!! note "Some example admonition"
    The first line in an admonition is highlighted correctly because code blocks are surrounded by black lines.

    This also means that everything after the first blank line is identified as a codeblock...

    ```sh
    touch file
    ```

    No matter what we do