Apply suggestion:

- Added `MediaSource.safeUrl` property replacing `withCleanUrl` method.
- Made `url` private so it can't be used externally.
- Reverted code in `CoilMediaFetcher`
- Also add tests

libraries/push/impl/src/main/kotlin/io/element/android/libraries/push/impl/notifications/NotificationMediaRepo.kt

@@ -101,7 +101,7 @@ class DefaultNotificationMediaRepo(
         }
     }
 
-    private fun MediaSource.cachedFile(): File? = mxcTools.mxcUri2FilePath(url)?.let {
+    private fun MediaSource.cachedFile(): File? = mxcTools.mxcUri2FilePath(safeUrl)?.let {
         File("${cacheDir.path}/$CACHE_NOTIFICATION_SUBDIR/$it")
     }
 }