Mostly revert versions back to June 3rd (#6614)

- Reverts all but monaco-editor to
46437d8942
- Also bumps webpack version forward

We've been having stability issues traced back to apparent issues in AWS
or smithy.

webpack.config.esm.ts

@@ -56,7 +56,7 @@ const hasGit = fs.existsSync(path.resolve(__dirname, '.git'));
 // Hack alert: due to a variety of issues, sometimes we need to change
 // the name here. Mostly it's things like webpack changes that affect
 // how minification is done, even though that's supposed not to matter.
-const webpackJsHack = '.v50.';
+const webpackJsHack = '.v51.';
 const plugins: Webpack.WebpackPluginInstance[] = [
     new MonacoEditorWebpackPlugin({
         languages: [