unable to open database file (Sqlite code 14), (OS error - 24:Too many open files)

Requesting too many downloads causes an exception on android

```
E/SQLiteLog(22812): (14) statement aborts at 17: [INSERT OR REPLACE INTO task(open_file_from_notification,headers,saved_dir,resumable,mime_type,file_name,progress,time_created,task_id,show_notification,url,status) VALUES (?,?,?,?,?,?
W/System.err(22812): android.database.sqlite.SQLiteCantOpenDatabaseException: unable to open database file (Sqlite code 14), (OS error - 24:Too many open files)
W/System.err(22812): at android.database.sqlite.SQLiteConnection.nativeExecuteForLastInsertedRowId(Native Method)
W/System.err(22812): at android.database.sqlite.SQLiteConnection.executeForLastInsertedRowId(SQLiteConnection.java:818)
W/System.err(22812): at android.database.sqlite.SQLiteSession.executeForLastInsertedRowId(SQLiteSession.java:803)
W/System.err(22812): at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:86)
W/System.err(22812): at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1729)
W/System.err(22812): at vn.hunghd.flutterdownloader.TaskDao.insertOrUpdateNewTask(TaskDao.java:54)
W/System.err(22812): at vn.hunghd.flutterdownloader.FlutterDownloaderPlugin.enqueue(FlutterDownloaderPlugin.java:182)
W/System.err(22812): at vn.hunghd.flutterdownloader.FlutterDownloaderPlugin.onMethodCall(FlutterDownloaderPlugin.java:82)
W/System.err(22812): at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:233)
W/System.err(22812): at io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart(DartMessenger.java:85)
W/System.err(22812): at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:818)
W/System.err(22812): at android.os.MessageQueue.nativePollOnce(Native Method)
W/System.err(22812): at android.os.MessageQueue.next(MessageQueue.java:379)
W/System.err(22812): at android.os.Looper.loop(Looper.java:144)
W/System.err(22812): at android.app.ActivityThread.main(ActivityThread.java:7529)
W/System.err(22812): at java.lang.reflect.Method.invoke(Native Method)
W/System.err(22812): at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
W/System.err(22812): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)
```

Start by reproducing the failure with many download requests, then inspect TaskDao.java at insertOrUpdateNewTask and FlutterDownloaderPlugin.java at enqueue using the provided stack trace. Done means repeated requests no longer produce SQLite code 14 or an OS error about too many open files.

Written by the indexing model from the issue text.