[vscode-graphql-syntax] Inconsistend highlighting of `extend` keyword

[LuudJanssen]

Current Behavior

In the following examples, the extend keyword is highlighted differently:

Expected Behavior

I would expect the extend keyword to be highlighted the same in both cases.

Looking at the grammars I get the feeling the extend keyword is not supported at all. In this case I'd expect the extend keyword to be supported by syntax highlighting.