Ensure the qhelp preview is refreshed after editing

This commit fixes a bug in the extension where the qhelp preview was not
being refreshed after the first time the preview was rendered. The
reason is that vscode will not refresh the markdown preview unless the
original file with the markdown in it is already open in the editor.

This fix will briefly open the raw markdown, refresh the preview and
close the raw markdown.

Author: aeisenberg

extensions/ql-vscode/src/common/commands.ts

@@ -59,6 +59,7 @@ type BuiltInVsCodeCommands = {
   // The codeQLDatabases.focus command is provided by VS Code because we've registered the custom view
   "codeQLDatabases.focus": () => Promise<void>;
   "markdown.showPreviewToSide": (uri: Uri) => Promise<void>;
+  "workbench.action.closeActiveEditor": () => Promise<void>;
   revealFileInOS: (uri: Uri) => Promise<void>;
   setContext: (
     key: `${"codeql" | "codeQL"}${string}`,

extensions/ql-vscode/src/language-support/query-editor.ts

@@ -1,4 +1,4 @@
-import { Uri, window } from "vscode";
+import { Uri, ViewColumn, window, workspace } from "vscode";
 import { CodeQLCliServer } from "../codeql-cli/cli";
 import { QueryRunner } from "../query-server";
 import { basename, join } from "path";
@@ -74,7 +74,16 @@ async function previewQueryHelp(
     const uri = Uri.file(absolutePathToMd);
     try {
       await cliServer.generateQueryHelp(pathToQhelp, absolutePathToMd);
+      // Open the raw markdown file as well as the rendered file.
+      // This will force the rendered page to refresh if there has been a change to the markdown.
+      const editor = await window.showTextDocument(uri, {
+        viewColumn: ViewColumn.Active,
+      });
       await commandManager.execute("markdown.showPreviewToSide", uri);
+      // close the editor we just opened. Users will see a brief flicker of this editor
+      // being opened, but doing so will ensure that the preview is refreshed.
+      await window.showTextDocument(uri);
+      await commandManager.execute("workbench.action.closeActiveEditor");
     } catch (e) {
       const errorMessage = getErrorMessage(e).includes(
         "Generating qhelp in markdown",