Fix incorrect external_acl_type codes

Fix incorrect external_acl_type codes

Documentation describes %USER_CA_CERT_* codes for outputing the CA cert
attributes. However the directive parser and internals were all
referencing it as %CA_CERT_*.

This updates the internals to match documentation, and adds an upgrade
notice for any installations using the old token name.

Also, Prepare external_acl_type format codes for libformat upgrade.
Add upgrade warnings for the %> and %< header codes which will change
radically in a future version when libformat is integrated.

Also, while we are at it support the other logformat codes which map 1:1
but silently for now and only on parse.