REORG: http: move the log encoding tables to log.c

REORG: http: move the log encoding tables to log.c

There are 3 tables in proto_http which are used exclusively by logs :
hdr_encode_map[], url_encode_map[] and http_encode_map[]. They indicate
what characters are safe to be emitted in logs depending on the part of
the message where they are placed. Let's move this to log.c, as well as
its initialization. It's worth noting that the rfc5424 map was already
initialized there.