Create a test case for a large group of peers bootstrapping from a webpeer

[anacrolix]

There's a common theme in some issues around a bunch of nodes bootstrapping themselves copies of some data, often from an original source that's a webseed. This would make a great test case. Things like total time and how much activity the individual nodes and webseed have could be measured.

[anacrolix]

https://github.com/anacrolix/torrent/tree/master/tests/peers-bootstrapping