pgsql: Add date_bin function

Add date_bin function

Similar to date_trunc, but allows binning by an arbitrary interval
rather than just full units.

Author: John Naylor <john(dot)naylor(at)enterprisedb(dot)com>
Reviewed-by: David Fetter <david(at)fetter(dot)org>
Reviewed-by: Isaac Morland <isaac(dot)morland(at)gmail(dot)com>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Artur Zakirov <zaartur(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/CACPNZCt4buQFRgy6DyjuZS-2aPDpccRkrJBmgUfwYc1KiaXYxg(at)mail(dot)gmail(dot)com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/49ab61f0bdc93984a8d36b602f6f2a15f09ebcc7

Modified Files
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doc/src/sgml/func.sgml | 50 ++++++++++++++++
src/backend/utils/adt/timestamp.c | 74 ++++++++++++++++++++++++
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.dat | 11 ++++
src/test/regress/expected/timestamp.out | 96 +++++++++++++++++++++++++++++++
src/test/regress/expected/timestamptz.out | 66 +++++++++++++++++++++
src/test/regress/sql/timestamp.sql | 62 ++++++++++++++++++++
src/test/regress/sql/timestamptz.sql | 42 ++++++++++++++
8 files changed, 402 insertions(+), 1 deletion(-)