In e17cc644 the Webpack build process for CodeMirror was changed.
For unknown reasons, not all plugins and modes were added.
This adds all plugins currently enabled in
https://github
.com/hedgedoc/CodeMirror/blob/951b3d94bb5ad9ac7b44642adbe595e843390506/release.sh
Signed-off-by: David Mehren <git@herrmehren.de>