pgsql: Unify JSON categorize type API and export for external use

Unify JSON categorize type API and export for external use

This essentially removes the JsonbTypeCategory enum and
jsonb_categorize_type() and integrates any jsonb-specific logic that
was in jsonb_categorize_type() into json_categorize_type(), now
moved to jsonfuncs.c.  The remaining JsonTypeCategory enum and
json_categorize_type() cover the needs of the callers in both json.c
and jsonb.c.  json_categorize_type() has grown a new parameter named
is_jsonb for callers to engage the jsonb-specific behavior of
json_categorize_type().

One notable change in the now exported API of json_categorize_type()
is that it now always returns *outfuncoid even though a caller may
have no need currently to see one.

This is in preparation of later commits to implement additional
SQL/JSON functions.

Co-authored-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/3c152a27b06313fe27bd47079658f928e291986b

Modified Files
--------------
src/backend/utils/adt/json.c      | 137 ++-------------------
src/backend/utils/adt/jsonb.c     | 245 +++++++++-----------------------------
src/backend/utils/adt/jsonfuncs.c | 111 +++++++++++++++++
src/include/utils/jsonfuncs.h     |  20 ++++
src/tools/pgindent/typedefs.list  |   1 -
5 files changed, 199 insertions(+), 315 deletions(-)