Nav: Fix main a11y issues (#80309)

* refactor: add nav announcement for screenreader

* refactor: add aria label

* refactor: add more aria labels

* refactor: aria labels

* refactor: remove aria-labels

* refactor: add aria-live

* refactor: add translations

* refactor: repair empty message

* refactor: repair empty message

* refactor: remove translation of empty message

* refactor: clean up

* refactor: change translation

public/app/core/components/AppChrome/DockedMegaMenu/MegaMenu.tsx

@@ -60,7 +60,7 @@ export const MegaMenu = React.memo(
         </div>
         <nav className={styles.content}>
           <CustomScrollbar showScrollIndicators hideHorizontalTrack>
-            <ul className={styles.itemList}>
+            <ul className={styles.itemList} aria-label={t('navigation.megamenu.list-label', 'Navigation')}>
               {navItems.map((link, index) => (
                 <Stack key={link.text} direction={index === 0 ? 'row-reverse' : 'row'} alignItems="center">
                   {index === 0 && (

public/app/core/components/AppChrome/DockedMegaMenu/MegaMenuItem.tsx

@@ -121,7 +121,9 @@ export function MegaMenuItem({ link, activeItem, level = 0, onClick }: Props) {
                 />
               ))
           ) : (
-            <div className={styles.emptyMessage}>{link.emptyMessage}</div>
+            <div className={styles.emptyMessage} aria-live="polite">
+              {link.emptyMessage}
+            </div>
           )}
         </ul>
       )}

public/locales/de-DE/grafana.json

@@ -974,6 +974,7 @@
     "megamenu": {
       "close": "Menü schließen",
       "dock": "Menü andocken",
+      "list-label": "",
       "undock": ""
     },
     "toolbar": {

public/locales/en-US/grafana.json

@@ -974,6 +974,7 @@
     "megamenu": {
       "close": "Close menu",
       "dock": "Dock menu",
+      "list-label": "Navigation",
       "undock": "Undock menu"
     },
     "toolbar": {

public/locales/es-ES/grafana.json

@@ -980,6 +980,7 @@
     "megamenu": {
       "close": "Cerrar menú",
       "dock": "Anclar el menú",
+      "list-label": "",
       "undock": "Desanclar el menú"
     },
     "toolbar": {

public/locales/fr-FR/grafana.json

@@ -980,6 +980,7 @@
     "megamenu": {
       "close": "Fermer le menu",
       "dock": "Ancrer le menu",
+      "list-label": "",
       "undock": ""
     },
     "toolbar": {

public/locales/pseudo-LOCALE/grafana.json

@@ -974,6 +974,7 @@
     "megamenu": {
       "close": "Cľőşę męʼnū",
       "dock": "Đőčĸ męʼnū",
+      "list-label": "Ńävįģäŧįőʼn",
       "undock": "Ůʼnđőčĸ męʼnū"
     },
     "toolbar": {

public/locales/zh-Hans/grafana.json

@@ -968,6 +968,7 @@
     "megamenu": {
       "close": "关闭菜单",
       "dock": "停靠菜单",
+      "list-label": "",
       "undock": ""
     },
     "toolbar": {