I see this post is old but it looks like it still gets a lot of views,...

You can also open a new window for VS Code, start a new or open a throw away project,.. this will allow you to create any language file you may need and drag and drop it on the tab bar of your original project. you will need to build it properly for intellisense to work or just duplicate your original project (rename to avoid confusion later). I think there are some good changelog extensions that can do the same, I'm already too heavy with the extensions so I just do this for quick stuff.