This adds 10MiB downloads hack to tornettools [Discussion]

[hiromipaw]

This adds the possibility to test 10MiB downloads with tornettools. See https://gitlab.torproject.org/jnewsome/sponsor-61-sims/-/issues/15

For the time being this is a test that is going to be used for the S61 simulation work within Tor. As mentioned in the gitlab issue we might think to add different download sizes to https://github.com/shadow/tornettools/blob/main/tornettools/generate_defaults.py later on.

Please not that I have added the option to parse the same download size from onionperf. This is not needed at this point since we do not have onionperf clients producing these tests. I have mainly added this for consistency and in case we might consider having a few onionperf clients producing these test in the not so far future.

[robgjansen]

It seems this is for discussion only - do not merge.