ssh: generate SK config file using private cbor and fido2 libs

Specify -lprivatecbor and -lprivatefido2 in OpenSSH's configure.ac, and
pass -I paths to libcbor and libfido2's contrib src location.

MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34440

(cherry picked from commit 73104d583850f7447ae1fe70c59a42e69d9d407c)