pgsql: Revoke PUBLIC CREATE from public schema, now owned by pg_databas

Revoke PUBLIC CREATE from public schema, now owned by pg_database_owner.

This switches the default ACL to what the documentation has recommended
since CVE-2018-1058.  Upgrades will carry forward any old ownership and
ACL.  Sites that declined the 2018 recommendation should take a fresh
look.  Recipes for commissioning a new database cluster from scratch may
need to create a schema, grant more privileges, etc.  Out-of-tree test
suites may require such updates.

Reviewed by Peter Eisentraut.

Discussion: https://postgr.es/m/20201031163518.GB4039133@rfd.leadboat.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/b073c3ccd06e4cb845e121387a43faa8c68a7b62

Modified Files
--------------
contrib/postgres_fdw/expected/postgres_fdw.out |  2 +-
contrib/postgres_fdw/sql/postgres_fdw.sql      |  2 +-
doc/src/sgml/ddl.sgml                          | 56 ++++++++++++++------------
doc/src/sgml/user-manag.sgml                   | 19 ++++-----
src/bin/initdb/initdb.c                        |  3 +-
src/bin/pg_dump/pg_dump.c                      | 28 ++++++++-----
src/bin/pg_dump/t/002_pg_dump.pl               | 19 ++++-----
src/include/catalog/catversion.h               |  2 +-
src/include/catalog/pg_namespace.dat           |  2 +-
src/pl/plperl/expected/plperl_setup.out        |  4 ++
src/pl/plperl/sql/plperl_setup.sql             |  4 ++
src/test/regress/input/tablespace.source       |  5 ++-
src/test/regress/output/tablespace.source      |  4 +-
13 files changed, 86 insertions(+), 64 deletions(-)