Fix for continuation behaviour on broken dataset archives due to starving download connections via HTTP-GET

[RuntimeRacer]

This PR proposes a (slightly hacky) fix for an Issue that can occur when downloading large dataset parts over unstable connections.
The underlying issue is also being discussed in #5594.

Issue Symptoms & Behaviour:

• Download of a large archive file during dataset download via HTTP-GET fails.
• An silent net exception (which I was unable to identify) is thrown within the tqdm download progress.
• Due to missing exception catch code, the above process just continues processing, assuming http_get completed successfully.
• Pending Archive file gets renamed to remove the .incomplete extension, despite not all data has been downloaded.
• Also, for reasons I did not investigate, there seems to be no real integrity check for the downloaded files; or it does not detect this problem. This is especially problematic, since the downloader script won't retry downloading this archive after CRC-Checking, even if it is being manually restarted / executed again after running into errors on extraction.

Fix proposal: Adding a retry mechanic for HTTP-GET downloads, which adds the following behaviour:

• Download Progress Thread checks for download size validity in case the HTTP connection starves mid download. If the check fails, a RuntimeError is thrown
• Cache Downloader code with retry mechanic monitors for an exception thrown by the download progress thread, and retries download with updated resume_size.
• Cache Downloader will not mark incomplete files which have thrown an exception during download, and exceeded retries, as complete.