function registerDocumentSemanticTokensProvider(languageSelector, provider) {
    const languageFeaturesService = StandaloneServices.get(ILanguageFeaturesService);
    return languageFeaturesService.documentSemanticTokensProvider.register(languageSelector, provider);
}
Register a document semantic tokens provider. A semantic tokens provider will complement and enhance a
simple top-down tokenizer. Simple top-down tokenizers can be set either via `setMonarchTokensProvider`
or `setTokensProvider`.

For the best user experience, register both a semantic tokens provider and a top-down tokenizer.