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/explore/NoDataSourceCallToAction.tsx

@@ -14,6 +14,7 @@ export const NoDataSourceCallToAction = () => {
       <a
         href="http://docs.grafana.org/administration/provisioning/#datasources?utm_source=explore"
         target="_blank"
+        rel="noopener"
         className="text-link"
       >
         Learn more