pgsql: Declare assorted array functions using anycompatible not anyelem

Declare assorted array functions using anycompatible not anyelement.

Convert array_append, array_prepend, array_cat, array_position,
array_positions, array_remove, array_replace, and width_bucket
to use anycompatiblearray.  This is a simple extension of commit
5c292e6b9 to hit some other places where there's a pretty obvious
gain in usability from doing so.

Ideally we'd also modify other functions taking multiple old-style
polymorphic arguments.  But most of the remainder are tied into one
or more operator classes, making any such change a much larger can of
worms than I desire to open right now.

Discussion: https://postgr.es/m/[email protected]

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/9e38c2bb5093ceb0c04d6315ccd8975bd17add66

Modified Files
--------------
doc/src/sgml/func.sgml                     | 50 ++++++++++++++++--------------
doc/src/sgml/xaggr.sgml                    |  4 +--
src/include/catalog/catversion.h           |  2 +-
src/include/catalog/pg_operator.dat        | 13 ++++----
src/include/catalog/pg_proc.dat            | 40 +++++++++++++++---------
src/test/regress/expected/arrays.out       | 12 +++++++
src/test/regress/expected/polymorphism.out | 10 +++---
src/test/regress/sql/arrays.sql            |  2 ++
src/test/regress/sql/polymorphism.sql      | 10 +++---
9 files changed, 86 insertions(+), 57 deletions(-)