Restrict SSR to paths in the sitemap

Because Angular SSR is not very efficient, after discussion with
the Google Scholar team we realized a compromise would be to only
use SSR for pages in the DSpace sitemap (and the home page).

src/config/ssr-config.interface.ts

@@ -20,4 +20,9 @@ export interface SSRConfig extends Config {
    * For improved SSR performance, DSpace defaults this to false (disabled).
    */
   inlineCriticalCss: boolean;
+
+  /**
+   * Paths to enable SSR for. Defaults to the home page and paths in the sitemap.
+   */
+  paths: Array<string>;
 }