Implement folding range refresh.

Author: toinehartman

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/routing/MultipleClientProxy.java

@@ -170,6 +170,11 @@ public CompletableFuture<Void> refreshDiagnostics() {
         return availableClient().refreshDiagnostics();
     }
 
+    @Override
+    public CompletableFuture<Void> refreshFoldingRanges() {
+        return availableClient().refreshFoldingRanges();
+    }
+
     @Override
     public CompletableFuture<Void> refreshInlayHints() {
         return availableClient().refreshInlayHints();