BUG/MEDIUM: ssl: fix build with AWS-LC

BUG/MEDIUM: ssl: fix build with AWS-LC

AWS-LC doesn't provide SSL_in_before(), and doesn't provide an easy way
to know if we already started the handshake or not. So instead, just add
a new field in ssl_sock_ctx, "can_write_early_data", that will be
initialized to 1, and will be set to 0 as soon as we start the
handshake.

This should be backported up to 2.8 with
13aa5616c9f99dbca0711fd18f716bd6f48eb2ae.

(cherry picked from commit b6702d53427a22725c125425552074c622c2f25d)
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
(cherry picked from commit 5ff41e99b8f68eb674231d99e546783b27c7e562)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>