Performance/Webpack: Introduces more aggressive code-splitting and other perf improvements (#18544)

* Performance/Webpack: Introduces more aggressive code-splitting and other perf improvements
- Introduces dynamic imports for built-in plugins
- Uses dynamic imports for various packages (rst2html, brace)
- Introduces route-based dynamic imports
- Splits angular and moment into separate bundles

public/app/features/plugins/PluginPage.tsx

@@ -278,7 +278,7 @@ class PluginPage extends PureComponent<Props, State> {
           {info.links.map(link => {
             return (
               <li key={link.url}>
-                <a href={link.url} className="external-link" target="_blank">
+                <a href={link.url} className="external-link" target="_blank" rel="noopener">
                   {link.name}
                 </a>
               </li>