Request-Line log format codes for split client and server view

Request-Line log format codes for split client and server view

Since URL-rewrite, adaptation and a number of other things can alter the
request as it goes through Squid it is useful to be able to log both the
original incoming and the final outgoing versions of these details.

This adds logformat codes to extend %rm %ru %rp and %rv with < and >
modifiers for in and outbound display.

The old tag versions are kept for now. There is still work to do cleaning
up the log data object which will clarify if the various data fields
which used to be passed to logging match either of the original or final
request data and can be obsoleted. It is already clear that the logged
path matches neither and contains some normalized version.