Code Mirror Syntax Highlighting: Support JSON

Currently syntax highlighting in source blocks support various languages - but one of the most common ones is not supported: JSON

While it can be argued that from a syntax highlighting perspective JSON could be treated as JS, semantically this is not true - if I have a json block this indicates JSON as a format, i.e. stored in a .json file. There are also syntactical differences between the two.

As JSON is an extremely common data exchange format I propose to add it to the list of supported languages.

I understand adding additional languages may slow down rendering, but there are quite a few far less common languages supported.

(There is a related idea for other languages; this request is limited to JSON)

Duplicate of Codeblock Syntax Highlighting support for more languages. I think there should be just one request to add more support