This patch completes the 0-rtt test to verify that early-data:1 is
properly emitted to the server in the relevant situations. We carefully
compare it with the expected values that are computed based on the TLS
version, the client and listener's support for 0-rtt and the resumption
status. A response header "x-early-data-test" is set to OK on success,
or KO on failure and the client tests this. The previous test is kept
as well. This was tested with quictls-1.1.1 and quictls-3.0.1 for TCP,
as well as aws-lc for QUIC.
These tests try all the combinations of {0,1}rtt <-> {0,1}rtt with
stateless and stateful tickets. They take into consideration the TLS
version to decide whether or not 0rtt should work. Since we cannot
use environment variables in the client, the tests are run in haproxy
itself where the frontends set a "x-early-rcvd-test" response header
that the client checks. At this stage, the test only verifies that
*some* early data were received.
Note that the tests are a bit complex because we need 4 listeners
for the various combinations of 0rtt/tickets, then we have to set
expectations based on the TLS version (1.2 vs 1.3), as well as the
session resumption status.
We have to set alpn on the server lines because currently our frontends
expect it for 0-rtt to work.
