Use labelDetails for completion item qualifiers (#278)

* Use labelDetails for completion item qualifiers

Use labelDetails.description instead of detail for qualifier text like
'full syntax' and 'list'. This renders the text inline after the label
in the completion menu, making variants immediately distinguishable
without hovering.

* Fix formatting

languageservice/src/complete.ts

@@ -194,7 +194,7 @@ export async function complete(
 
     const item: CompletionItem = {
       label: value.label,
-      detail: value.detail,
+      labelDetails: value.labelDetail ? {description: value.labelDetail} : undefined,
       filterText: value.filterText,
       sortText: value.sortText,
       documentation: value.description && {