fix bug https://github.com/AriaLyy/Aria/issues/407

移除`DownloadGroupEntity`字段`groupHash`的主键约束，`DownloadEntity`字段`groupHash`的外键约束，`TaskRecord`字段`dGroupHash`的外键约束
优化关联查询的性能

app/src/main/java/com/arialyy/simple/core/download/m3u8/M3U8VodModule.java

@@ -34,7 +34,7 @@ public class M3U8VodModule extends BaseViewModule {
   // m3u8测试集合：http://www.voidcn.com/article/p-snaliarm-ct.html
   //private final String defUrl = "https://www.gaoya123.cn/2019/1557993797897.m3u8";
   // 多码率地址：
-  private final String defUrl = "http://ivi.bupt.edu.cn/hls/cctv6hd.m3u8";
+  private final String defUrl = "http://devimages.apple.com/iphone/samples/bipbop/bipbopall.m3u8";
   private final String filePath =
       Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath()
           + "/1557993797897.ts";

app/src/main/java/com/arialyy/simple/core/download/multi_download/FileListAdapter.java

@@ -73,6 +73,7 @@ final class FileListAdapter extends AbsRVAdapter<FileListEntity, FileListAdapter
                 .setSubFileName(Arrays.asList(item.names))
                 .setDirPath(item.downloadPath)
                 .setGroupAlias(item.name)
+                .unknownSize()
                 .start();
           } else {
             Aria.download(getContext())

app/src/main/java/com/arialyy/simple/core/download/multi_download/MultiTaskActivity.java

@@ -136,6 +136,9 @@ public class MultiTaskActivity extends BaseActivity<ActivityMultiBinding> {
   }
 
   @DownloadGroup.onTaskFail void groupTaskFail(DownloadGroupTask task) {
+    if (task == null){
+      return;
+    }
     mAdapter.updateBtState(task.getKey(), true);
     Log.d(TAG, String.format("group【%s】fail", task.getTaskName()));
   }