getSingleFile() doesn't return fully downloaded file

[jasonkaruza]

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For those that are attempting to use getSingleFile() before using video_player to play a downloaded video, even when doing an await on getSingleFile() the File is very often returned before the video is downloaded fully, which causes the video player to fail initialization.

No attempts at re-downloading or re-initilializing seemed to work, so dropped use of flutter_cache_manager and switched to downloading the file locally using dio package. This obviously negates the benefit of cache management, but it seemed to respect await properly by ensuring that the file returned is completely downloaded before returning.