[CST-4880] Add ServerCheckGuard in order to show internal server error page when rest server is not available

src/app/app-routing-paths.ts

@@ -89,6 +89,12 @@ export function getPageNotFoundRoute() {
   return `/${PAGE_NOT_FOUND_PATH}`;
 }
 
+export const INTERNAL_SERVER_ERROR = '500';
+
+export function getPageInternalServerErrorRoute() {
+  return `/${INTERNAL_SERVER_ERROR}`;
+}
+
 export const INFO_MODULE_PATH = 'info';
 export function getInfoModulePath() {
   return `/${INFO_MODULE_PATH}`;