pgsql: Remove factorial operators, leaving only the factorial() functio

Remove factorial operators, leaving only the factorial() function.

The "!" operator is our only built-in postfix operator.  Remove it,
on the way to removal of grammar support for postfix operators.

There is also a "!!" prefix operator, but since it's been marked
deprecated for most of its existence, we might as well remove it too.

Also zap the SQL alias function numeric_fac(), which seems to have
equally little reason to live.

Mark Dilger, based on work by myself and Robert Haas;
review by John Naylor

Discussion: https://postgr.es/m/38ca86db-42ab-9b48-2902-337a0d6b8311@2ndquadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/76f412ab310554acb970a0b73c8d1f37f35548c6

Modified Files
--------------
contrib/postgres_fdw/expected/postgres_fdw.out |  8 -------
contrib/postgres_fdw/sql/postgres_fdw.sql      |  1 -
doc/src/sgml/func.sgml                         | 30 --------------------------
src/include/catalog/catversion.h               |  3 +--
src/include/catalog/pg_operator.dat            |  6 ------
src/include/catalog/pg_proc.dat                |  4 ----
src/test/regress/expected/create_operator.out  | 20 ++++++++---------
src/test/regress/expected/numeric.out          | 26 ++++++++--------------
src/test/regress/sql/create_operator.sql       | 20 ++++++++---------
src/test/regress/sql/numeric.sql               |  8 +++----
10 files changed, 33 insertions(+), 93 deletions(-)