clear the ServiceWorker cache on logout (#854)

* Update authProvider.js

This fixes https://github.com/navidrome/navidrome/issues/613 : clears the ServiceWorker cache on logout. Based on this code: https://developer.mozilla.org/en-US/docs/Web/API/CacheStorage/keys . Seems to work on macOS and iOS, but please test on other platforms.

* Format code with `prettier`

Co-authored-by: Deluan <deluan@navidrome.org>

ui/src/authProvider.js

@@ -59,6 +59,7 @@ const authProvider = {
   logout: () => {
     stopEventStream()
     removeItems()
+    clearServiceWorkerCache()
     return Promise.resolve()
   },
 
@@ -97,6 +98,12 @@ const removeItems = () => {
   localStorage.removeItem('subsonic-token')
 }
 
+const clearServiceWorkerCache = () => {
+  caches.keys().then(function (keyList) {
+    for (let key of keyList) caches.delete(key)
+  })
+}
+
 const generateSubsonicSalt = () => {
   const h = md5(uuidv4())
   return h.slice(0, 6)