pgsql: Make pg_basebackup ask the server to estimate the total backup s

Make pg_basebackup ask the server to estimate the total backup size, by default.

This commit changes pg_basebackup so that it specifies PROGRESS option in
BASE_BACKUP replication command whether --progress is specified or not.
This causes the server to estimate the total backup size and report it in
pg_stat_progress_basebackup.backup_total, by default. This is reasonable
default because the time required for the estimation would not be so large
in most cases.

Also this commit adds new option --no-estimate-size to pg_basebackup.
This option prevents the server from the estimation, and so is useful to
avoid such estimation time if it's too long.

Author: Fujii Masao
Reviewed-by: Magnus Hagander, Amit Langote
Discussion: https://postgr.es/m/CABUevEyDPPSjP7KRvfTXPdqOdY5aWNkqsB5aAXs3bco5ZwtGHg@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/fab13dc50ba5e7a12b474a7366024681bc169ac8

Modified Files
--------------
doc/src/sgml/monitoring.sgml | 10 ++++-----
doc/src/sgml/ref/pg_basebackup.sgml | 39 +++++++++++++++++++++--------------
src/bin/pg_basebackup/pg_basebackup.c | 16 +++++++++++++-
3 files changed, 44 insertions(+), 21 deletions(-)