test against the autobahn testing utility

[the-mikedavis]

https://github.com/crossbario provides a testing suite for RFC conformance for websockets in https://github.com/crossbario/autobahn-testsuite

It's not super clear from the docs how one actually performs the test against the fuzz server (see crossbario/autobahn-testsuite#103) but the gun testing suite has some clues https://github.com/ninenines/gun/blob/fe25965f3a2f1347529fec8c7afa981313378e31/test/ws_autobahn_SUITE.erl.

[the-mikedavis]

gonna call this ✔️ for now but I'd like to revisit this and add the performance measurements

once #1 is implemented, we can also check against sections 12 & 13