Similar to boringssl, reuse the NSS client image for the NSS server test
against the tris client. Bump the NSS version to 3.34.1 gain support
for TLS 1.3 keylogging which is useful while debugging.
Adjust read check to fix intermittent NSS test failures:
https://github.com/cloudflare/tls-tris/issues/58
Prepare framework for testing tls-tris as client against other servers.
Currently only boringssl is implemented, but the idea is to add support
for others too (NSS, OpenSSL, picotls, tris, ...).
To test multiple certificate types, copy ecdsa.pem and rsa.pem from
tris-localserver for boringssl. The boringssl image is reused for the
server since the binaries were built anyway. Revision is bumped to
something to fix a build error and make the -loop and -www options work.
There is no reason a server can't just send a CloseNotify in its first
flight, and then close the connection without reading the 0-RTT data.
Also, it's not expected of Close to block on reading, and interlocking
with a Read can cause a deadlock.
Fixes NCC-2016-001
