pgsql: Log remote NOTICE, WARNING, and similar messages using ereport()

Log remote NOTICE, WARNING, and similar messages using ereport().

Previously, NOTICE, WARNING, and similar messages received from remote
servers over replication, postgres_fdw, or dblink connections were printed
directly to stderr on the local server (e.g., the subscriber). As a result,
these messages lacked log prefixes (e.g., timestamp), making them harder
to trace and correlate with other log entries.

This commit addresses the issue by introducing a custom notice receiver
for replication, postgres_fdw, and dblink connections. These messages
are now logged via ereport(), ensuring they appear in the logs with proper
formatting and context, which improves clarity and aids in debugging.

Author: Vignesh C <vignesh21@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/CALDaNm2xsHpWRtLm-VL_HJCsaE3+1Y_n-jDEAr3-suxVqc3xoQ@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/112faf1378ee62db75cd9e3223c86bf53b8c2736

Modified Files
--------------
contrib/dblink/dblink.c                            |  7 +++++
contrib/postgres_fdw/connection.c                  |  3 +++
.../libpqwalreceiver/libpqwalreceiver.c            |  3 +++
src/include/libpq/libpq-be-fe-helpers.h            | 30 ++++++++++++++++++++++
4 files changed, 43 insertions(+)