[PATCH] external_acl_type format cleanup pt 1

Removes the _external_acl_format::format_type enum from external_acl.cc
by replacing it with Format::ByteCode_t enum.

Several missing logformat codes related to URL display have been added
to the logformat token set for general use.

Several of the external ACL format codes have been added to
Format::ByteCode_t without equivalent logformat TokenTableEntry's at
this stage as both desirable token naming and access to the data to
produce them generically is unclear.

The external_acl_type parser is updated to accept logformat tokens
wherever an equivalent exists and map directly to the ByteCode_t values.

The mgr:config report dumper is also updated to output the logformat
tokens. But as yet the official deprecation has not been done in
squid.conf. That I think should wait on full conversion to using the
Format:: API.

Amos