Move any code specific to log_destination=csvlog to its own file
The recent refactoring done in
ac7c807 makes this move possible and
simple, as this just moves some code around. This reduces the size of
elog.c by 7%.
Author: Michael Paquier, Sehrope Sarkuni
Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/CAH7T-aqswBM6JWe4pDehi1uOiufqe06DJWaU5=X7dDLyqUExHg@mail.gmail.com
simply moves the routines related to csvlog into their own file