MediaColumns has been deprecated

I'm using flutter_downloader-1.8.4 in my project and this is causing the following warning:

```
C:\Program Files\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_downloader-1.8.4\android\src\main\java\vn\hunghd\flutterdownloader\DownloadWorker.java:539: warning: [deprecation] DATA in MediaColumns has been deprecated
new String[]{MediaStore.Files.FileColumns.DATA},
^
C:\Program Files\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_downloader-1.8.4\android\src\main\java\vn\hunghd\flutterdownloader\DownloadWorker.java:548: warning: [deprecation] DATA in MediaColumns has been deprecated
return cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.DATA));
^
C:\Program Files\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_downloader-1.8.4\android\src\main\java\vn\hunghd\flutterdownloader\DownloadWorker.java:757: warning: [deprecation] getExternalStorageDirectory() in Environment has been deprecated
File externalStorageDir = Environment.getExternalStorageDirectory();
^
C:\Program Files\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_downloader-1.8.4\android\src\main\java\vn\hunghd\flutterdownloader\DownloadWorker.java:772: warning: [deprecation] DATA in MediaColumns has been deprecated
values.put(MediaStore.Images.Media.DATA, filePath);
^
C:\Program Files\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_downloader-1.8.4\android\src\main\java\vn\hunghd\flutterdownloader\DownloadWorker.java:787: warning: [deprecation] DATA in MediaColumns has been deprecated
values.put(MediaStore.Video.Media.DATA, filePath);
^
C:\Program Files\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_downloader-1.8.4\android\src\main\java\vn\hunghd\flutterdownloader\FlutterDownloaderPlugin.java:361: warning: [deprecation] DATA in MediaColumns has been deprecated
String imageSelection = MediaStore.Images.Media.DATA + " = ?";
^
C:\Program Files\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_downloader-1.8.4\android\src\main\java\vn\hunghd\flutterdownloader\FlutterDownloaderPlugin.java:362: warning: [deprecation] DATA in MediaColumns has been deprecated
String videoSelection = MediaStore.Video.Media.DATA + " = ?";
```

Review android/src/main/java/vn/hunghd/flutterdownloader/DownloadWorker.java around lines 539, 548, 757, 772, and 787, then FlutterDownloaderPlugin.java around lines 361-362. Start by tracing the deprecated MediaStore DATA and Environment storage calls and confirm the Android APIs they target. Done means the reported deprecation warnings are resolved without breaking download, image, or video path handling.

Written by the indexing model from the issue text.