Broken syntax highlighting with variable directives

[romshark]

According to the GraphQL specification from October 2021 directives can be applied to operation variables.
However, GraphiQL 1.8.2 doesn't seem to handle them properly. The syntax highlighting is breaking when you add a directive between variable definitions.

[acao]

It seems the spec authors forgot to open a PR for graphiql!

[acao]

there are four places this could be an issue:

1. the monaco grammar for graphql, managed by microsoft in monaco-editor repository
2. the vscode textmate grammars
3. the codemirror-graphql has a modeFactory implementation
4. the cm6-graphql has a lezer grammar implementation