Create a whole chain of Ed488 certificates so that we can use it at security
level 4 (192 bit). We had an 2048 bit RSA (112 bit, level 2) root sign the
Ed488 certificate using SHA256 (128 bit, level 3).
Reviewed-by: NMatt Caswell <matt@openssl.org>
GH: #10785
(cherry picked from commit 77c4d3972400adf1bcb76ceea359f5453cc3e8e4)