pgsql: For inplace update durability, make heap_update() callers wait.

For inplace update durability, make heap_update() callers wait.

The previous commit fixed some ways of losing an inplace update. It
remained possible to lose one when a backend working toward a
heap_update() copied a tuple into memory just before inplace update of
that tuple. In catalogs eligible for inplace update, use LOCKTAG_TUPLE
to govern admission to the steps of copying an old tuple, modifying it,
and issuing heap_update(). This includes MERGE commands. To avoid
changing most of the pg_class DDL, don't require LOCKTAG_TUPLE when
holding a relation lock sufficient to exclude inplace updaters.
Back-patch to v12 (all supported versions). In v13 and v12, "UPDATE
pg_class" or "UPDATE pg_database" can still lose an inplace update. The
v14+ UPDATE fix needs commit 86dc90056dfdbd9d1b891718d2e5614e3e432f35,
and it wasn't worth reimplementing that fix without such infrastructure.

Reviewed by Nitin Motiani and (in earlier versions) Heikki Linnakangas.

Discussion: https://postgr.es/m/20231027214946.79.nmisch@google.com

Branch
------
REL_16_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/51ff46de29f67d73549b2858f57e77ada8513369

Modified Files
--------------
src/backend/access/heap/README.tuplock | 42 ++++++
src/backend/access/heap/heapam.c | 150 ++++++++++++++++++++-
src/backend/access/index/genam.c | 4 +-
src/backend/catalog/aclchk.c | 9 +-
src/backend/catalog/catalog.c | 9 ++
src/backend/commands/dbcommands.c | 25 +++-
src/backend/commands/indexcmds.c | 7 +-
src/backend/commands/tablecmds.c | 28 +++-
src/backend/executor/execMain.c | 6 +
src/backend/executor/execReplication.c | 6 +-
src/backend/executor/nodeModifyTable.c | 87 ++++++++++--
src/backend/utils/cache/relcache.c | 9 +-
src/backend/utils/cache/syscache.c | 117 ++++++++++++++++
src/include/nodes/execnodes.h | 3 +
src/include/storage/lockdefs.h | 2 +
src/include/utils/syscache.h | 5 +
.../isolation/expected/intra-grant-inplace.out | 14 +-
src/test/isolation/specs/eval-plan-qual.spec | 2 +-
src/test/isolation/specs/intra-grant-inplace.spec | 12 +-
19 files changed, 488 insertions(+), 49 deletions(-)