Expand tests for factorial
Move from int4 to numeric test. (They were originally int4 functions,
but were reimplemented for numeric in
04a4821adef38155b7920ba9eb83c4c3c29156f8.) Add some tests for edge
cases.
Discussion: https://www.postgresql.org/message-id/flat/
6ce1df0e-86a3-e544-743a-
f357ff663f68%402ndquadrant.com