Fix external_acl problems after trunk r14351

Fix external_acl problems after trunk r14351
(Support logformat %macros in external_acl_type format).

The above changes created the following problems:
 - external_acl requires AccessLogEntry but ALE is not available
   in many cases such as ssl_bump ACLs.
 - The %<cert_subject stopped working because it was supported by
   external_acl code and not by logformat code.

This patch:
  - Passes AccessLogEntry in most cases.
    For example, PeerConnector-related classes are now covered.
  - Implements the %<cert_subject formating code for logformat.

This is a Measurement Factory project.