Ruby: add print-cfg query

ruby/ql/lib/ide-contextual-queries/printCfg.ql

@@ -0,0 +1,22 @@
+/**
+ * @name Print CFG
+ * @description Produces a representation of a file's Control Flow Graph.
+ *              This query is used by the VS Code extension.
+ * @id rb/print-cfg
+ * @kind graph
+ * @tags ide-contextual-queries/print-cfg
+ */
+
+private import codeql.ruby.controlflow.internal.ControlFlowGraphImplShared::TestOutput
+private import codeql.IDEContextual
+
+/**
+ * Gets the source file to generate a CFG from.
+ */
+external string selectedSourceFile();
+
+class MyRelevantNode extends RelevantNode {
+  MyRelevantNode() {
+    this.getScope().getLocation().getFile() = getFileBySourceArchiveName(selectedSourceFile())
+  }
+}