pgsql: Show more detail in nbtree rmgr descriptions.

Show more detail in nbtree rmgr descriptions.

Show a detailed description of the page offset number arrays that appear
in certain nbtree WAL records.

Also brings nbtree desc routines in line with the guidelines established
by recent commit 7d8219a4.

Author: Melanie Plageman <melanieplageman(at)gmail(dot)com>
Reviewed-By: Peter Geoghegan <pg(at)bowt(dot)ie>
Discussion: https://postgr.es/m/flat/20230109215842.fktuhesvayno6o4g%40awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1c453cfd8976d9c6451ba45e27bf30375d574312

Modified Files
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src/backend/access/rmgrdesc/nbtdesc.c | 87 ++++++++++++++++++++++++----
src/backend/access/rmgrdesc/rmgrdesc_utils.c | 6 ++
src/include/access/rmgrdesc_utils.h | 1 +
3 files changed, 83 insertions(+), 11 deletions(-)