Extended test_suite_ssl testing for TLS HS defragmentation

[mpg]

We need some extra testing that can't be done with ssl-opt.sh but need the extra powers we have in test_suite_ssl. This task covers those bits, that are not covered by #9887 or #9987.

• Receive an incomplete sequence of fragments, then a non-handshake message.
• Receive fragments whose total announced size announced is over some relevant limit, even though each fragment is under the limit.
• Receive fragments whose total size (intermediate while we're waiting for more fragments) is over some relevant limit, even though each fragment is under the limit.
• If not covered by Extended ssl-opt tests for TLS HS defragmentation #9987: in TLS 1.2, the ClientHello that initiates a renegotiation is fragmented. It's OK for us not to work in this case, but if we fail it must be cleanly.