pgsql: Rename GUC logical_decoding_mode to logical_replication_mode.

Rename GUC logical_decoding_mode to logical_replication_mode.

Rename the developer option 'logical_decoding_mode' to the more flexible
name 'logical_replication_mode' because doing so will make it easier to
extend this option in the future to help test other areas of logical
replication.

Currently, it is used on the publisher side to allow streaming or
serializing each change in logical decoding. In the upcoming patch, we are
planning to use it on the subscriber. On the subscriber, it will allow
serializing the changes to file and notifies the parallel apply workers to
read and apply them at the end of the transaction.

We discussed exposing this parameter as a subscription option but
it did not seem advisable since it is primarily used for testing/debugging
and there is no other such parameter. We also discussed having separate
GUCs for publisher and subscriber but for current testing/debugging
requirements, one GUC is sufficient.

Author: Hou Zhijie
Reviewed-by: Peter Smith, Kuroda Hayato, Sawada Masahiko, Amit Kapila
Discussion: https://postgr.es/m/CAD21AoAy2c=Mx=FTCs+EwUsf2kQL5MmU3N18X84k0EmCXntK4g@mail.gmail.com
Discussion: https://postgr.es/m/CAA4eK1+wyN6zpaHUkCLorEWNx75MG0xhMwcFhvjqm2KURZEAGw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1e8b61735cfb1a4feb72cb9ea83db690fedbfef1

Modified Files
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doc/src/sgml/config.sgml | 8 ++++----
src/backend/replication/logical/reorderbuffer.c | 14 +++++++-------
src/backend/utils/misc/guc_tables.c | 16 ++++++++--------
src/include/replication/reorderbuffer.h | 11 ++++++-----
src/test/subscription/t/016_stream_subxact.pl | 2 +-
src/test/subscription/t/018_stream_subxact_abort.pl | 2 +-
src/test/subscription/t/019_stream_subxact_ddl_abort.pl | 2 +-
src/test/subscription/t/023_twophase_stream.pl | 2 +-
src/tools/pgindent/typedefs.list | 2 +-
9 files changed, 30 insertions(+), 29 deletions(-)