Bug 2038: check reply_body_max_size before ICAP

Bug 2038: check reply_body_max_size before ICAP

Moved maxReplyBodySize-related code from ClientHttpRequest to HttpReply
because server-side needs it too to check limits before ICAP sucks all the
data in.

Calculating limit requires knowing HttpRequest because it affects expected
content length. Since I did not find a single place where any HttpReply would
be guaranteed to be given the request to calculate the limit, we now supply
the request whenever a limit check is performed. The limit calculation result
is cached and the calculation should not be repeated.