pgsql: Add mem_exceeded_count column to pg_stat_replication_slots.

Add mem_exceeded_count column to pg_stat_replication_slots.

This commit introduces a new column mem_exceeded_count to the
pg_stat_replication_slots view. This counter tracks how often the
memory used by logical decoding exceeds the logical_decoding_work_mem
limit. The new statistic helps users determine whether exceeding the
logical_decoding_work_mem limit is a rare occurrences or a frequent
issue, information that wasn't available through existing statistics.

Bumps catversion.

Author: Bertrand Drouvot <bertranddrouvot(dot)pg(at)gmail(dot)com>
Reviewed-by: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
Reviewed-by: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Reviewed-by: shveta malik <shveta(dot)malik(at)gmail(dot)com>
Reviewed-by: Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>
Reviewed-by: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Discussion: https://postgr.es/m/978D21E8-9D3B-40EA-A4B1-F87BABE7868C@yesql.se

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d3b6183dd988928dd369b4b7d641917e77f1ae4e

Modified Files
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contrib/test_decoding/expected/stats.out | 71 +++++++++++++------------
contrib/test_decoding/sql/stats.sql | 13 +++--
doc/src/sgml/monitoring.sgml | 11 ++++
src/backend/catalog/system_views.sql | 1 +
src/backend/replication/logical/logical.c | 8 ++-
src/backend/replication/logical/reorderbuffer.c | 34 +++++++++---
src/backend/utils/activity/pgstat_replslot.c | 1 +
src/backend/utils/adt/pgstatfuncs.c | 19 ++++---
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.dat | 6 +--
src/include/pgstat.h | 1 +
src/include/replication/reorderbuffer.h | 3 ++
src/test/regress/expected/rules.out | 3 +-
13 files changed, 113 insertions(+), 60 deletions(-)