Add support for quick eval count to the query runner (#2417)

* Add support for quick eval count to the query runner

This only adds support internally to the query runner,
without any UI support.

* Fix some tests

extensions/ql-vscode/src/data-extensions-editor/external-api-usage-query.ts

@@ -78,7 +78,11 @@ export async function runQuery({
 
   const queryRun = queryRunner.createQueryRun(
     databaseItem.databaseUri.fsPath,
-    { queryPath: queryFile, quickEvalPosition: undefined },
+    {
+      queryPath: queryFile,
+      quickEvalPosition: undefined,
+      quickEvalCountOnly: false,
+    },
     false,
     getOnDiskWorkspaceFolders(),
     extensionPacks,