Add syntax highlight for language "cpp"

[omovomo]

Is this request related to a problem? Please describe.

A clear and concise description of what the problem is (e.g. "I'm always frustrated when […]").

Describe the solution you'd like

A clear and concise description of what you want to happen.

Additional context

Add any other information or screenshots about the feature request here (e.g. a gif showing how another tool does it).