add option to calculate CompletionItemKind for keywords (#1499)

Author: cdietrich

packages/langium/src/lsp/completion/completion-provider.ts

@@ -472,12 +472,16 @@ export class DefaultCompletionProvider implements CompletionProvider {
         }
         acceptor(context, {
             label: keyword.value,
-            kind: CompletionItemKind.Keyword,
+            kind: this.getKeywordCompletionItemKind(keyword),
             detail: 'Keyword',
             sortText: '1'
         });
     }
 
+    protected getKeywordCompletionItemKind(_keyword: ast.Keyword): CompletionItemKind {
+        return CompletionItemKind.Keyword;
+    }
+
     protected filterKeyword(context: CompletionContext, keyword: ast.Keyword): boolean {
         // Filter out keywords that do not contain any word character
         return /\p{L}/u.test(keyword.value);