When the `SimplifiedVAHTTP01` feature flag is enabled we need to
preserve query parameters when reconstructing a redirect URL for the
resolved IP address.
To add integration testing for this condition the Boulder tools images
are updated to in turn pull in an updated `pebble-challtestsrv` command
that tracks request history.
A new Python wrapper for the `pebble-challtestsrv` HTTP API is added to
centralize interacting with the chall test srv to add mock data and to
get the history of HTTP requests that have been processed.
Daniel McCarney