Display length and bounds histograms in pg_stats
Values corresponding to STATISTIC_KIND_RANGE_LENGTH_HISTOGRAM and
STATISTIC_KIND_BOUNDS_HISTOGRAM were not exposed to pg_stats when these
slot kinds were introduced in
918eee0c49.
This commit adds the missing fields to pg_stats.
Catversion is bumped.
Discussion: https://postgr.es/m/flat/
b67d8b57-9357-7e82-a2e7-
f6ce6eaeec67@postgrespro.ru
Author: Egor Rogov, Soumyadeep Chakraborty
Reviewed-by: Tomas Vondra, Justin Pryzby, Jian He