pgsql: psql: Show all query results by default

psql: Show all query results by default

Previously, psql printed only the last result if a command string
returned multiple result sets.  Now it prints all of them.  The
previous behavior can be obtained by setting the psql variable
SHOW_ALL_RESULTS to off.

This is a significantly enhanced version of
3a5130672296ed4e682403a77a9a3ad3d21cef75 (that was later reverted).
There is also much more test coverage for various psql features now.

Author: Fabien COELHO <coelho@cri.ensmp.fr>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: "Iwata, Aya" <iwata.aya@jp.fujitsu.com> (earlier version)
Reviewed-by: Daniel Verite <daniel@manitou-mail.org> (earlier version)
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> (earlier version)
Reviewed-by: vignesh C <vignesh21@gmail.com> (earlier version)
Discussion: https://www.postgresql.org/message-id/flat/alpine.DEB.2.21.1904132231510.8961@lancre

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/7844c9918a43b494adde3575891d217a37062378

Modified Files
--------------
.../expected/pg_stat_statements.out                |  25 +
doc/src/sgml/ref/psql-ref.sgml                     |  29 +-
src/bin/psql/common.c                              | 524 ++++++++++++---------
src/bin/psql/help.c                                |   2 +
src/bin/psql/settings.h                            |   1 +
src/bin/psql/startup.c                             |  10 +
src/bin/psql/t/001_basic.pl                        |   2 +-
src/bin/psql/tab-complete.c                        |   2 +-
src/test/regress/expected/copyselect.out           |  14 +-
src/test/regress/expected/psql.out                 | 242 ++++++++++
src/test/regress/expected/transactions.out         |  58 ++-
src/test/regress/sql/copyselect.sql                |   4 +-
src/test/regress/sql/psql.sql                      | 141 ++++++
src/test/regress/sql/transactions.sql              |   2 +-
14 files changed, 801 insertions(+), 255 deletions(-)