pgsql: Remove artificial restrictions on which node types have out/read

Remove artificial restrictions on which node types have out/read funcs.

The initial version of gen_node_support.pl manually excluded most
utility statement node types from having out/read support, and
also some raw-parse-tree-only node types.  That was mostly to keep
the output comparable to the old hand-maintained code.  We'd like
to have out/read support for utility statements, for debugging
purposes and so that they can be included in new-style SQL functions;
so it's time to lift that restriction.

Most if not all of the previously-excluded raw-parse-tree-only node
types can appear in expression subtrees of utility statements, so
they have to be handled too.

We don't quite have full read support yet; certain custom_read_write
node types need to have their handwritten read functions implemented
before that will work.

Doing this allows us to drop the previous hack in _outQuery to not
dump the utilityStmt field in most cases, which means we no longer
need manually-maintained out/read functions for Query, so get rid
of those in favor of auto-generating them.

Fix a couple of omissions in gen_node_support.pl that are exposed
through having to handle more node types.

catversion bump forced because somebody was sloppy about the field
order in the manually-maintained Query out/read functions.
(Committers should note that almost all changes in parsenodes.h
are now grounds for a catversion bump.)

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/ff33a8c8874b43ec55d517ce0612ed79ad08a38a

Modified Files
--------------
src/backend/nodes/gen_node_support.pl | 39 ++++++-------------
src/backend/nodes/outfuncs.c          | 73 -----------------------------------
src/backend/nodes/readfuncs.c         | 50 ------------------------
src/include/catalog/catversion.h      |  6 ++-
src/include/nodes/parsenodes.h        | 10 ++---
5 files changed, 19 insertions(+), 159 deletions(-)