Various accessibility improvements

* Add announcement element with `aria-live`
* Add skip to main content element

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/router/error.ts

@@ -1,5 +1,6 @@
 import { RouteConfig } from "vue-router";
 import { ImportedComponent } from "vue/types/options";
+import { i18n } from "@/utils/i18n";
 
 export enum ErrorRouteName {
   ERROR = "Error",
@@ -11,5 +12,8 @@ export const errorRoutes: RouteConfig[] = [
     name: ErrorRouteName.ERROR,
     component: (): Promise<ImportedComponent> =>
       import(/* webpackChunkName: "Error" */ "../views/Error.vue"),
+    meta: {
+      announcer: { message: (): string => i18n.t("Error") as string },
+    },
   },
 ];