pgsql: Add STREAM_START/STREAM_STOP for transactional messages during d

Add STREAM_START/STREAM_STOP for transactional messages during decoding.

In test_decoding module, when skip_empty_xacts option was specified, add
stream_start/stop for streaming transactional messages. This makes the
handling of transactional messages stream consistent irrespective of
whether skip_empty_xacts option was specified.

Commit 26dd0284b9 made a similar change for non-streaming messages but
forgot to update the streaming cases.

Author: Peter Smith
Reviewed-by: Amit Kapila
Discussion: http://postgr.es/m/OS0PR01MB5716AEBD2988F8F5E9D5985794DFA@OS0PR01MB5716.jpnprd01.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/57891c256c345451b91ddb67a8e2a9c5eca9ae1c

Modified Files
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contrib/test_decoding/expected/stream.out          |  5 ++++-
contrib/test_decoding/expected/twophase_stream.out | 10 ++++++++--
contrib/test_decoding/test_decoding.c              | 13 +++++++++++++
3 files changed, 25 insertions(+), 3 deletions(-)