See if we can use Semantic Highlighting in the editor as well

[tstirrat15]

authzed/spicedb-vscode#37

We use Monaco, which is what VSCode is based on, so if it's possible to use semantic highlighting here too that'd be awesome.

[tstirrat15]

Yes: https://microsoft.github.io/monaco-editor/typedoc/functions/languages.registerDocumentSemanticTokensProvider.html

Last thing to check is whether it's usable in the docs site. I think that's the last place we're using tmlanguages.