pgsql: Track invalidation_reason in pg_replication_slots.

Track invalidation_reason in pg_replication_slots.

Till now, the reason for replication slot invalidation is not tracked
directly in pg_replication_slots. A recent commit 007693f2a3 added
'conflict_reason' to show the reasons for slot conflict/invalidation, but
only for logical slots.

This commit adds a new column 'invalidation_reason' to show invalidation
reasons for both physical and logical slots. And, this commit also turns
'conflict_reason' text column to 'conflicting' boolean column (effectively
reverting commit 007693f2a3). The 'conflicting' column is true for
invalidation reasons 'rows_removed' and 'wal_level_insufficient' because
those make the slot conflict with recovery. When 'conflicting' is true,
one can now look at the new 'invalidation_reason' column for the reason
for the logical slot's conflict with recovery.

The new 'invalidation_reason' column will also be useful to track other
invalidation reasons in the future commit.

Author: Bharath Rupireddy
Reviewed-by: Bertrand Drouvot, Amit Kapila, Shveta Malik
Discussion: https://www.postgresql.org/message-id/ZfR7HuzFEswakt/a%40ip-10-97-1-34.eu-west-3.compute.internal
Discussion: https://www.postgresql.org/message-id/CALj2ACW4aUe-_uFQOjdWCEN-xXoLGhmvRFnL8SNw_TZ5nJe+aw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/6ae701b4378db2284c77314560e95a93d0ba9484

Modified Files
--------------
doc/src/sgml/ref/pgupgrade.sgml                    |  4 +-
doc/src/sgml/system-views.sgml                     | 25 +++++++----
src/backend/catalog/system_views.sql               |  3 +-
src/backend/replication/logical/slotsync.c         |  2 +-
src/backend/replication/slot.c                     | 49 ++++++++++------------
src/backend/replication/slotfuncs.c                | 25 +++++++----
src/bin/pg_upgrade/info.c                          |  4 +-
src/include/catalog/catversion.h                   |  2 +-
src/include/catalog/pg_proc.dat                    |  6 +--
src/include/replication/slot.h                     |  2 +-
.../recovery/t/035_standby_logical_decoding.pl     | 35 ++++++++--------
.../recovery/t/040_standby_failover_slots_sync.pl  |  4 +-
src/test/regress/expected/rules.out                |  5 ++-
13 files changed, 94 insertions(+), 72 deletions(-)