pgsql: Print WAL logical message contents in pg_waldump

Print WAL logical message contents in pg_waldump

This helps debuggability when looking at WAL streams containing logical
messages.

Author: Ashutosh Bapat <ashutosh.bapat@2ndquadrant.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CAExHW5sWx49rKmXbg5H1Xc1t+nRv9PaYKQmgw82HPt6vWDVmDg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/9f1cf97bb5387a6243c8a6c9725616ef7447962e

Modified Files
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src/backend/access/rmgrdesc/logicalmsgdesc.c | 17 ++++++++++++++---
src/backend/replication/logical/message.c    |  1 +
src/include/replication/message.h            |  5 ++---
3 files changed, 17 insertions(+), 6 deletions(-)