pgsql: Pull up ANY-SUBLINK with the necessary lateral support.

Pull up ANY-SUBLINK with the necessary lateral support.

For ANY-SUBLINK, we adopted a two-stage pull-up approach to handle
different types of scenarios. In the first stage, the sublink is pulled up
as a subquery. Because of this, when writing this code, we did not have
the ability to perform lateral joins, and therefore, we were unable to
pull up Var with varlevelsup=1. Now that we have the ability to use
lateral joins, we can eliminate this limitation.

Author: Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com>
Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Richard Guo <guofenglinux(at)gmail(dot)com>
Reviewed-by: Alena Rybakina <lena(dot)ribackina(at)yandex(dot)ru>
Reviewed-by: Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/9f133763961e280d8ba692bcad0b061b861e9138

Modified Files
--------------
contrib/postgres_fdw/expected/postgres_fdw.out | 6 +-
contrib/postgres_fdw/sql/postgres_fdw.sql | 4 +-
src/backend/optimizer/plan/subselect.c | 17 +++-
src/test/regress/expected/join.out | 14 +--
src/test/regress/expected/subselect.out | 126 +++++++++++++++++++++++++
src/test/regress/sql/join.sql | 8 +-
src/test/regress/sql/subselect.sql | 37 ++++++++
7 files changed, 192 insertions(+), 20 deletions(-)