unit-test: Improve test suite compatiblity with newer OpenSSL

[xnox]

No impact or changes to production scripts.

More recent OpenSSL requires additional keyUsage & basic constraints
to be set on the test certificates. Adjust test key generation to have
them, note production certificates already have all of those settings.

Fingerprint parsing had mismatched capitaliation - asking OpenSSL to
provide lowercase fingerprint and matching for uppercase one. Make
them consistent.

Without these changes test suite has these errors:

CN = intermediate.managedssh.amazonaws.com
error 89 at 1 depth lookup: Basic Constraints of CA cert not marked critical
CN = intermediate.managedssh.amazonaws.com
error 92 at 1 depth lookup: CA cert does not include key usage extension
CN = managedssh.amazonaws.com
error 92 at 2 depth lookup: CA cert does not include key usage extension
error /dev/shm/tmp-i7Fdjp2e/cert.pem: verification failed
mixed FAILED
EXPECTED: exit 0 with output
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAQmefSRJyiAUSlICBKAO+4heV1kkA46PQm5ZQVxxhv7pF1yWWLhgFJ9IG9qmeeKIQ3bzKBzGv5UHSeJbuRfwY6ZtKynBfjzN1WRuYY2oaDjlh2vzK5WgvVttUJk8oAYcZM2h+aXpJtlWV95yqaTSD4XcuWOg3E3KCTcK2Xf/BaB4IN/pJF1SyuLg5ygWh0dKi4X+tH81aHcEg8pWfDLFkdKUF0d6GwIi+iCJxfb5bubY3/+0qYc0IqWOxa4vf6ggW7yI5m3mOX0kRuOAPEY/6fe4KfcGqLZvraKe1ZLYMgQUKuawhpPzooVeI/EtI3gtFDC0b8YAPjA2CUDc/3APR
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAQmefSRJyiAUSlICBKAO+4heV1kkA46PQm5ZQVxxhv7pF1yWWLhgFJ9IG9qmeeKIQ3bzKBzGv5UHSeJbuRfwY6ZtKynBfjzN1WRuYY2oaDjlh2vzK5WgvVttUJk8oAYcZM2h+aXpJtlWV95yqaTSD4XcuWOg3E3KCTcK2Xf/BaB4IN/pJF1SyuLg5ygWh0dKi4X+tH81aHcEg8pWfDLFkdKUF0d6GwIi+iCJxfb5bubY3/+0qYc0IqWOxa4vf6ggW7yI5m3mOX0kRuOAPEY/6fe4KfcGqLZvraKe1ZLYMgQUKuawhpPzooVeI/EtI3gtFDC0b8YAPjA2CUDc/3APR
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAQmefSRJyiAUSlICBKAO+4heV1kkA46PQm5ZQVxxhv7pF1yWWLhgFJ9IG9qmeeKIQ3bzKBzGv5UHSeJbuRfwY6ZtKynBfjzN1WRuYY2oaDjlh2vzK5WgvVttUJk8oAYcZM2h+aXpJtlWV95yqaTSD4XcuWOg3E3KCTcK2Xf/BaB4IN/pJF1SyuLg5ygWh0dKi4X+tH81aHcEg8pWfDLFkdKUF0d6GwIi+iCJxfb5bubY3/+0qYc0IqWOxa4vf6ggW7yI5m3mOX0kRuOAPEY/6fe4KfcGqLZvraKe1ZLYMgQUKuawhpPzooVeI/EtI3gtFDC0b8YAPjA2CUDc/3APR
ACTUAL: exit 2 with output

With these changes in place:

$ ./bin/unit_test_suite.sh
empty PASSED
invalid-signature PASSED
different-fingerprint PASSED
expired-timestamp PASSED
invalid-instance PASSED
missing-data PASSED
mixed PASSED
valid-key PASSED