feat(mobile): show local assets (#905)

* introduce Asset as composition of AssetResponseDTO and AssetEntity

* filter out duplicate assets (that are both local and remote, take only remote for now)

* only allow remote images to be added to albums

* introduce ImmichImage to render Asset using local or remote data

* optimized deletion of local assets

* local video file playback

* allow multiple methods to wait on background service finished

* skip local assets when adding to album from home screen

* fix and optimize delete

* show gray box placeholder for local assets

* add comments

* fix bug: duplicate assets in state after onNewAssetUploaded

mobile/android/app/src/main/kotlin/com/example/mobile/BackupWorker.kt

@@ -134,13 +134,13 @@ class BackupWorker(ctx: Context, params: WorkerParameters) : ListenableWorker(ct
     }
 
     private fun stopEngine(result: Result?) {
+        clearBackgroundNotification()
+        engine?.destroy()
+        engine = null
         if (result != null) {
             Log.d(TAG, "stopEngine result=${result}")
             resolvableFuture.set(result)
         }
-        engine?.destroy()
-        engine = null
-        clearBackgroundNotification()
         waitOnSetForegroundAsync()
     }