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(at)cri(dot)ensmp(dot)fr>
Reviewed-by: Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>
Reviewed-by: "Iwata, Aya" <iwata(dot)aya(at)jp(dot)fujitsu(dot)com> (earlier version)
Reviewed-by: Daniel Verite <daniel(at)manitou-mail(dot)org> (earlier version)
Reviewed-by: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> (earlier version)
Reviewed-by: vignesh C <vignesh21(at)gmail(dot)com> (earlier version)
Discussion: https://www.postgresql.org/message-id/flat/alpine(dot)DEB(dot)2(dot)21(dot)1904132231510(dot)8961(at)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(-)